Merge pull request #5055 from edx/waheed/bld1221-fix-video-not-play-in-firefox-on-speed-change

Fixed video not playing after changing speed to anything other than 1.

common/lib/xmodule/xmodule/js/spec/video/video_player_spec.js

@@ -496,7 +496,7 @@ function (VideoPlayer) {
                     state.speed = '2.0';
                     state.videoPlayer.onPlay();
                     expect(state.videoPlayer.setPlaybackRate)
-                        .toHaveBeenCalledWith('2.0');
+                        .toHaveBeenCalledWith('2.0', true);
                     state.videoPlayer.onPlay();
                     expect(state.videoPlayer.setPlaybackRate.calls.length)
                         .toEqual(1);

common/lib/xmodule/xmodule/js/src/video/03_video_player.js

@@ -96,7 +96,7 @@ function (HTML5Video, Resizer) {
             $(window).on('unload', state.saveState);
 
             if (!state.isFlashMode() && state.speed != '1.0') {
-                state.videoPlayer.setPlaybackRate(state.speed);
+                state.videoPlayer.setPlaybackRate(state.speed, true);
             }
         });
 
@@ -351,18 +351,17 @@ function (HTML5Video, Resizer) {
         }
     }
 
-    function setPlaybackRate(newSpeed) {
+    function setPlaybackRate(newSpeed, useCueVideoById) {
         var duration = this.videoPlayer.duration(),
             time = this.videoPlayer.currentTime,
             methodName, youtubeId;
 
+        // If useCueVideoById is true it will reload video again.
+        // Used useCueVideoById to fix the issue video not playing if we change
+        // the speed before playing the video.
         if (
-            this.isHtml5Mode() &&
-            !(
-                this.browserIsFirefox &&
-                newSpeed === '1.0' &&
-                this.isYoutubeType()
-            )
+          this.isHtml5Mode() && !(this.browserIsFirefox &&
+          (useCueVideoById || newSpeed === '1.0') && this.isYoutubeType())
         ) {
             this.videoPlayer.player.setPlaybackRate(newSpeed);
         } else {
@@ -385,7 +384,10 @@ function (HTML5Video, Resizer) {
             // is in a PAUSED state.
             //
             // Why? This is how the YouTube API is implemented.
-            this.videoPlayer.updatePlayTime(time);
+            // sjson.search() only works if time is defined.
+            if (!_.isUndefined(time)) {
+                this.videoPlayer.updatePlayTime(time);
+            }
             if (time > 0 && this.isFlashMode()) {
                 this.videoPlayer.seekTo(time);
                 this.trigger(