diff --git a/content/base/src/nsGkAtomList.h b/content/base/src/nsGkAtomList.h
index a9ef184eaa8..71fe08cb8b9 100644
--- a/content/base/src/nsGkAtomList.h
+++ b/content/base/src/nsGkAtomList.h
@@ -115,6 +115,9 @@ GK_ATOM(attribute, "attribute")
 GK_ATOM(attributeSet, "attribute-set")
 GK_ATOM(aural, "aural")
 GK_ATOM(_auto, "auto")
+#ifdef MOZ_MEDIA
+GK_ATOM(autobuffer, "autobuffer")
+#endif
 GK_ATOM(autocheck, "autocheck")
 GK_ATOM(autocomplete, "autocomplete")
 #ifdef MOZ_MEDIA
diff --git a/content/html/content/public/nsHTMLMediaElement.h b/content/html/content/public/nsHTMLMediaElement.h
index 8611c54b7a2..48a4ef65f13 100644
--- a/content/html/content/public/nsHTMLMediaElement.h
+++ b/content/html/content/public/nsHTMLMediaElement.h
@@ -311,6 +311,11 @@ protected:
    */
   void ChangeDelayLoadStatus(PRBool aDelay);
 
+  /**
+   * If we suspended downloading after the first frame, unsuspend now.
+   */
+  void StopSuspendingAfterFirstFrame();
+
   /**
    * Called when our channel is redirected to another channel.
    * Updates our mChannel reference to aNewChannel.
@@ -435,4 +440,12 @@ protected:
   // PR_TRUE when we've got a task queued to call SelectResource(),
   // or while we're running SelectResource().
   PRPackedBool mIsRunningSelectResource;
+
+  // PR_TRUE if we suspended the decoder because we were paused,
+  // autobuffer and autoplay were not set, and we loaded the first frame.
+  PRPackedBool mSuspendedAfterFirstFrame;
+
+  // PR_TRUE if we are allowed to suspend the decoder because we were paused,
+  // autobuffer and autoplay were not set, and we loaded the first frame.
+  PRPackedBool mAllowSuspendAfterFirstFrame;
 };
diff --git a/content/html/content/src/nsHTMLMediaElement.cpp b/content/html/content/src/nsHTMLMediaElement.cpp
index b3864f99d83..34cb3860a38 100644
--- a/content/html/content/src/nsHTMLMediaElement.cpp
+++ b/content/html/content/src/nsHTMLMediaElement.cpp
@@ -296,6 +296,7 @@ NS_INTERFACE_MAP_END_INHERITING(nsGenericHTMLElement)
 NS_IMPL_URI_ATTR(nsHTMLMediaElement, Src, src)
 NS_IMPL_BOOL_ATTR(nsHTMLMediaElement, Controls, controls)
 NS_IMPL_BOOL_ATTR(nsHTMLMediaElement, Autoplay, autoplay)
+NS_IMPL_BOOL_ATTR(nsHTMLMediaElement, Autobuffer, autobuffer)
 
 /* readonly attribute nsIDOMHTMLMediaElement mozAutoplayEnabled; */
 NS_IMETHODIMP nsHTMLMediaElement::GetMozAutoplayEnabled(PRBool *aAutoplayEnabled)
@@ -382,6 +383,8 @@ void nsHTMLMediaElement::AbortExistingLoads()
   mLoadedFirstFrame = PR_FALSE;
   mAutoplaying = PR_TRUE;
   mIsLoadingFromSrcAttribute = PR_FALSE;
+  mSuspendedAfterFirstFrame = PR_FALSE;
+  mAllowSuspendAfterFirstFrame = PR_TRUE;
 
   // TODO: The playback rate must be set to the default playback rate.
 
@@ -646,6 +649,8 @@ NS_IMETHODIMP nsHTMLMediaElement::GetCurrentTime(float *aCurrentTime)
 
 NS_IMETHODIMP nsHTMLMediaElement::SetCurrentTime(float aCurrentTime)
 {
+  StopSuspendingAfterFirstFrame();
+
   if (!mDecoder)
     return NS_ERROR_DOM_INVALID_STATE_ERR;
 
@@ -772,7 +777,9 @@ nsHTMLMediaElement::nsHTMLMediaElement(nsINodeInfo *aNodeInfo, PRBool aFromParse
     mIsRunningLoadMethod(PR_FALSE),
     mIsLoadingFromSrcAttribute(PR_FALSE),
     mDelayingLoadEvent(PR_FALSE),
-    mIsRunningSelectResource(PR_FALSE)
+    mIsRunningSelectResource(PR_FALSE),
+    mSuspendedAfterFirstFrame(PR_FALSE),
+    mAllowSuspendAfterFirstFrame(PR_TRUE)
 {
   RegisterFreezableElement();
 }
@@ -790,8 +797,21 @@ nsHTMLMediaElement::~nsHTMLMediaElement()
   }
 }
 
+void nsHTMLMediaElement::StopSuspendingAfterFirstFrame()
+{
+  mAllowSuspendAfterFirstFrame = PR_FALSE;
+  if (!mSuspendedAfterFirstFrame)
+    return;
+  mSuspendedAfterFirstFrame = PR_FALSE;
+  if (mDecoder) {
+    mDecoder->Resume();
+  }
+}
+
 NS_IMETHODIMP nsHTMLMediaElement::Play()
 {
+  StopSuspendingAfterFirstFrame();
+
   if (mNetworkState == nsIDOMHTMLMediaElement::NETWORK_EMPTY) {
     nsresult rv = Load();
     NS_ENSURE_SUCCESS(rv, rv);
@@ -859,16 +879,23 @@ nsresult nsHTMLMediaElement::SetAttr(PRInt32 aNameSpaceID, nsIAtom* aName,
   nsresult rv = 
     nsGenericHTMLElement::SetAttr(aNameSpaceID, aName, aPrefix, aValue,
                                     aNotify);
-  if (aNotify &&
-      aNameSpaceID == kNameSpaceID_None &&
-      aName == nsGkAtoms::src &&
-      mLoadWaitStatus == WAITING_FOR_SRC_OR_SOURCE) 
-  {
-    // A previous load algorithm instance is waiting on a src
-    // addition, resume the load. It is waiting at "step 1 of the load
-    // algorithm".
-    mLoadWaitStatus = NOT_WAITING;
-    QueueSelectResourceTask();
+  if (aNotify && aNameSpaceID == kNameSpaceID_None) {
+    if (aName == nsGkAtoms::src) {
+      if (mLoadWaitStatus == WAITING_FOR_SRC_OR_SOURCE) {
+        // A previous load algorithm instance is waiting on a src
+        // addition, resume the load. It is waiting at "step 1 of the load
+        // algorithm".
+        mLoadWaitStatus = NOT_WAITING;
+        QueueSelectResourceTask();
+      }
+    } else if (aName == nsGkAtoms::autoplay) {
+      StopSuspendingAfterFirstFrame();
+      if (mReadyState == nsIDOMHTMLMediaElement::HAVE_ENOUGH_DATA) {
+        NotifyAutoplayDataReady();
+      }
+    } else if (aName == nsGkAtoms::autobuffer) {
+      StopSuspendingAfterFirstFrame();
+    }
   }
 
   return rv;
@@ -1217,6 +1244,15 @@ void nsHTMLMediaElement::FirstFrameLoaded()
 {
   ChangeReadyState(nsIDOMHTMLMediaElement::HAVE_CURRENT_DATA);
   ChangeDelayLoadStatus(PR_FALSE);
+
+  NS_ASSERTION(!mSuspendedAfterFirstFrame, "Should not have already suspended");
+
+  if (mDecoder && mAllowSuspendAfterFirstFrame && mPaused &&
+      !HasAttr(kNameSpaceID_None, nsGkAtoms::autoplay) &&
+      !HasAttr(kNameSpaceID_None, nsGkAtoms::autobuffer)) {
+    mSuspendedAfterFirstFrame = PR_TRUE;
+    mDecoder->Suspend();
+  }
 }
 
 void nsHTMLMediaElement::ResourceLoaded()
diff --git a/content/media/video/public/nsMediaDecoder.h b/content/media/video/public/nsMediaDecoder.h
index 75e3ee704c2..e7a9fe8b666 100644
--- a/content/media/video/public/nsMediaDecoder.h
+++ b/content/media/video/public/nsMediaDecoder.h
@@ -213,13 +213,16 @@ public:
   virtual void Shutdown();
 
   // Suspend any media downloads that are in progress. Called by the
-  // media element when it is sent to the bfcache. Call on the main
-  // thread only.
+  // media element when it is sent to the bfcache, or when we need
+  // to throttle the download. Call on the main thread only. This can
+  // be called multiple times, there's an internal "suspend count".
   virtual void Suspend() = 0;
 
   // Resume any media downloads that have been suspended. Called by the
-  // media element when it is restored from the bfcache. Call on the
-  // main thread only.
+  // media element when it is restored from the bfcache, or when we need
+  // to stop throttling the download. Call on the main thread only.
+  // The download will only actually resume once as many Resume calls
+  // have been made as Suspend calls.
   virtual void Resume() = 0;
 
   // Returns a weak reference to the media element we're decoding for,
diff --git a/content/media/video/test/Makefile.in b/content/media/video/test/Makefile.in
index 687f6d8a8b6..d16c63d21b4 100644
--- a/content/media/video/test/Makefile.in
+++ b/content/media/video/test/Makefile.in
@@ -46,6 +46,7 @@ include $(topsrcdir)/config/rules.mk
 _TEST_FILES = \
 		can_play_type_ogg.js \
 		can_play_type_wave.js \
+		test_autobuffer.html \
 		test_autoplay.html \
 		test_can_play_type.html \
 		test_constants.html \
@@ -64,6 +65,7 @@ _TEST_FILES += \
 		dynamic_redirect.sjs \
 		test_access_control.html \
 		file_access_controls.html \
+		test_autobuffer2.html \
 		test_bug448534.html \
 		test_bug461281.html \
 		test_bug468190.html \
diff --git a/content/media/video/test/test_autobuffer.html b/content/media/video/test/test_autobuffer.html
new file mode 100644
index 00000000000..4bee15055db
--- /dev/null
+++ b/content/media/video/test/test_autobuffer.html
@@ -0,0 +1,45 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=479863
+-->
+<head>
+  <title>Test for Bug 479863</title>
+  <script type="application/javascript" src="/MochiKit/packed.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=479863">Mozilla Bug 479863</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+
+<video id='v1' onerror="event.stopPropagation();"></video><audio id='a1' onerror="ev
+ent.stopPropagation();"></audio>
+<video id='v2' onerror="event.stopPropagation();" autobuffer></video><audio id='a2' on
+error="event.stopPropagation();" autobuffer></audio>
+
+<pre id="test">
+<script type="application/javascript">
+var v1 = document.getElementById('v1');
+var a1 = document.getElementById('a1');
+var v2 = document.getElementById('v2');
+var a2 = document.getElementById('a2');
+ok(!v1.autobuffer, "v1.autobuffer should be false by default");
+ok(!a1.autobuffer, "v1.autobuffer should be false by default");
+ok(v2.autobuffer, "v2.autobuffer should be true");
+ok(a2.autobuffer, "v2.autobuffer should be true");
+
+v1.autobuffer = true;
+a1.autobuffer = true;
+ok(v1.autobuffer, "video.autobuffer not true");
+ok(a1.autobuffer, "audio.autobuffer not true");
+is(v1.getAttribute("autobuffer"), "", "video autobuffer attribute not set");
+is(a1.getAttribute("autobuffer"), "", "video autobuffer attribute not set");
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/content/media/video/test/test_autobuffer2.html b/content/media/video/test/test_autobuffer2.html
new file mode 100644
index 00000000000..7c48ecdb3f2
--- /dev/null
+++ b/content/media/video/test/test_autobuffer2.html
@@ -0,0 +1,73 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=479863
+-->
+<head>
+  <title>Test for Bug 479863</title>
+  <script type="application/javascript" src="/MochiKit/packed.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript" src="use_large_cache.js"></script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=479863">Mozilla Bug 479863</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+
+<script type="application/javascript">
+var stalls = { v1:false, v2:false, v3:false, v4:false, v5:false, v6:false };
+var loads = { v1:false, v2:false, v3:false, v4:false, v5:false, v6:false };
+var totalLoadEvents = 0;
+var expectedLoadEvents = 6;
+
+function loaded(event) {
+  loads[event.target.id] = true;
+  ++totalLoadEvents;
+  if (totalLoadEvents == expectedLoadEvents) {
+    ok(stalls.v1, "v1 should stall");
+    // We might get accidental stalls on very slow machines, so lets not test these
+    // ok(!stalls.v2, "v2 should not stall");
+    // ok(!stalls.v3, "v3 should not stall");
+    ok(stalls.v4, "v4 should stall");
+    ok(stalls.v5, "v5 should stall");
+    ok(stalls.v6, "v6 should stall");
+    ok(loads.v1, "v1 should load after setting autobuffer");
+    ok(loads.v2, "v2 should load");
+    ok(loads.v3, "v3 should load");
+    ok(loads.v4, "v4 should load after calling play()");
+    ok(loads.v5, "v5 should load after seeking");
+    ok(loads.v6, "v6 should load after setting autoplay");
+    SimpleTest.finish();
+  }
+}
+function stalled(event) {
+  stalls[event.target.id] = true;
+  if (event.target.id == "v1") {
+    event.target.autobuffer = true;
+  } else if (event.target.id == "v4") {
+    event.target.play();
+  } else if (event.target.id == "v5") {
+    event.target.currentTime = 0.1;
+  } else if (event.target.id == "v6") {
+    event.target.autoplay = true;
+  }
+}
+</script>
+
+<video id='v1' src="seek.ogv" onstalled="stalled(event)" onload="loaded(event)"></video>
+<video id='v2' src="seek.ogv" onstalled="stalled(event)" onload="loaded(event)" autobuffer></video>
+<video id='v3' src="seek.ogv" onstalled="stalled(event)" onload="loaded(event)" autoplay></video>
+<video id='v4' src="seek.ogv" onstalled="stalled(event)" onload="loaded(event)"></video>
+<video id='v5' src="seek.ogv" onstalled="stalled(event)" onload="loaded(event)"></video>
+<video id='v6' src="seek.ogv" onstalled="stalled(event)" onload="loaded(event)"></video>
+
+<pre id="test">
+<script type="application/javascript">
+SimpleTest.waitForExplicitFinish();
+</script>
+</pre>
+</body>
+</html>
diff --git a/content/media/video/test/test_autoplay.html b/content/media/video/test/test_autoplay.html
index 1df518eab42..8666712f051 100644
--- a/content/media/video/test/test_autoplay.html
+++ b/content/media/video/test/test_autoplay.html
@@ -21,9 +21,11 @@ ok(v2.autoplay, "v2.autoplay should be true");
 ok(a2.autoplay, "v2.autoplay should be true");
 
 v1.autoplay = true;
-v1.autoplay = true;
+a1.autoplay = true;
 ok(v1.autoplay, "video.autoplay not true");
-ok(v1.autoplay, "audio.autoplay not true");
+ok(a1.autoplay, "audio.autoplay not true");
+is(v1.getAttribute("autoplay"), "", "video autoplay attribute not set");
+is(a1.getAttribute("autoplay"), "", "video autoplay attribute not set");
 </script>
 </pre>
 </body>
diff --git a/dom/interfaces/html/nsIDOMHTMLMediaElement.idl b/dom/interfaces/html/nsIDOMHTMLMediaElement.idl
index 7592b98c782..c952dfc177e 100644
--- a/dom/interfaces/html/nsIDOMHTMLMediaElement.idl
+++ b/dom/interfaces/html/nsIDOMHTMLMediaElement.idl
@@ -56,7 +56,7 @@
 #endif
 %}
 
-[scriptable, uuid(0ccf2f96-af4c-4af2-b684-b28f3369827f)]
+[scriptable, uuid(23fb201a-556d-4054-9885-6437e8910296)]
 interface nsIDOMHTMLMediaElement : nsIDOMHTMLElement
 {
   // error state
@@ -90,6 +90,7 @@ interface nsIDOMHTMLMediaElement : nsIDOMHTMLElement
   readonly attribute boolean ended;
   readonly attribute boolean mozAutoplayEnabled;
            attribute boolean autoplay;
+           attribute boolean autobuffer;
   void play();
   void pause();