Fix video links.

docs/device-mode.html

@@ -11,10 +11,10 @@
   <object width="425"
           height="355">
     <param name="movie"
-        value="https://www.youtube.com/watch?v=FrAZWiMWRa4">
+        value="https://www.youtube.com/v/FrAZWiMWRa4">
     <param name="wmode"
         value="transparent">
-    <embed src="https://www.youtube.com/watch?v=FrAZWiMWRa4"
+    <embed src="https://www.youtube.com/v/FrAZWiMWRa4"
         type="application/x-shockwave-flash"
         wmode="transparent"
         width="425"