The <video> tag's "playing" event should fire whenever the video begins playback. If a video's currentTime attribute is set after the video ends, it begins playing again without firing this event. Also, if <video>.play() is called after the video ends, the player seeks back to <video>.startTime and plays, but doesn't fire the playing event. These issues can be annoying when creating custom controls for a <video>.
This issue looks to be same as https://bugs.webkit.org/show_bug.cgi?id=60972 which is resolved.
*** This bug has been marked as a duplicate of bug 60972 ***