Something that happens 100% of the time for me, using Windows 10 and Firefox 51/Edge/Chrome 56/Internet Explorer (so maybe any browser?):
- Get to the bottom of a thread with a lot of posts and videos - Post Your Favorite Youtube Vids works.
- Refresh the page.
- Play some videos - or just one. Pause in the middle or watch to the end, doesn’t matter.
- Mouse wheel up 20 posts or drag the browser’s scroll bar up to the top to make it load more of the thread.
- Within a few seconds (of IE not shitting itself anymore), everything you’ve played so far will (try to) play again.