I don't know if this is the only cause of the bug, but if you let the player to play video to its very end so the player closes itself, next time you open a video it will launch multiple times(and the problem will persist until you close app as you have said). I have tried it several times and it worked. So basically, just close the video before player does it, and you should be fine.

However, I found one more issue. Certain videos look
like this:

(link to video)
It stays in this state for the whole video and happens always not just sometimes.