I'm a big fan of image annotation for MediaWiki, and I was wondering if it could be done with videos. This is a pretty good step in the right direction. We get not only videos, but multi-lingual subtitles for the videos too (or annotations, if that's what you want to call them). Anyone can update or add more subtitles, in whatever languages they speak.
I'm pretty sure there's a few bugs in that widget, but I've tested it enough to be confident that it should work reasonably well. Let me know if you notice anything seriously wrong with it, and also if you have your own tweaks to add. It's got a fair bit of "polish" that I've put into it, based on my previous MediaWiki template programming experience and lessons, but I'm sure there's ways it can be improved further.
Thanks to all Widget extension contributors that made this possible!