diff --git a/toolkit/content/widgets/videocontrols.xml b/toolkit/content/widgets/videocontrols.xml
index 6c4cb237c831..8a82146f47d9 100644
--- a/toolkit/content/widgets/videocontrols.xml
+++ b/toolkit/content/widgets/videocontrols.xml
@@ -1234,12 +1234,38 @@
       },
 
       onFullscreenChange() {
+        this.updateOrientationState(this.isVideoInFullScreen());
         if (this.isVideoInFullScreen()) {
           Utils._hideControlsTimeout = setTimeout(this._hideControlsFn, this.HIDE_CONTROLS_TIMEOUT_MS);
         }
         this.setFullscreenButtonState();
       },
 
+      updateOrientationState(lock) {
+        if (!this.video.mozOrientationLockEnabled) {
+          return;
+        }
+        if (lock) {
+          if (this.video.mozIsOrientationLocked) {
+            return;
+          }
+          let dimenDiff = this.video.videoWidth - this.video.videoHeight;
+          if (dimenDiff > 0) {
+            this.video.mozIsOrientationLocked = window.screen.mozLockOrientation("landscape");
+          } else if (dimenDiff < 0) {
+            this.video.mozIsOrientationLocked = window.screen.mozLockOrientation("portrait");
+          } else {
+            this.video.mozIsOrientationLocked = window.screen.mozLockOrientation(window.screen.orientation);
+          }
+        } else {
+          if (!this.video.mozIsOrientationLocked) {
+            return;
+          }
+          window.screen.mozUnlockOrientation();
+          this.video.mozIsOrientationLocked = false;
+        }
+      },
+
       clickToPlayClickHandler(e) {
         if (e.button != 0) {
           return;
@@ -1836,6 +1862,7 @@
   <destructor>
     <![CDATA[
     this.Utils.terminateEventListeners();
+    this.Utils.updateOrientationState(false);
     // randomID used to be a <field>, which meant that the XBL machinery
     // undefined the property when the element was unbound. The code in
     // this file actually depends on this, so now that randomID is an