Our old video player frontend doesn't quite work right on mobile so we've been migrating towards a modern one based on video.js, which does work on mobile and can integrate with our Safari compatibility shim.
It's been blocked on some issues with subtitle compatibility, which I'll be working on in the next couple weeks as the VP9 conversion is now underway.
Once that's resolved we should be able to deploy the update and have working video on iOS and better video on Android, with subtitles when available.
-- brion