Bug 877025. Don't set 'firstShow' on the controls for a video that is already playing. r=dolske

toolkit/content/widgets/videocontrols.xml

@@ -1635,8 +1635,8 @@
               // makes that happen. But because of bug 718107 this init() method
               // may be called again when we switch in or out of fullscreen
               // mode. So we only set firstShow if we're not autoplaying and
-              // if we are at the beginning of the video
-              if (!video.autoplay && this.Utils.dynamicControls &&
+              // if we are at the beginning of the video and not already playing
+              if (!video.autoplay && this.Utils.dynamicControls && video.paused &&
                   video.currentTime === 0)
                 this.firstShow = true;