In the next couple weeks I'm planning to start switching our video transcode output from WebM VP8/Vorbis to the newer WebM VP9/Opus profile, which saves us about 38% on file size and bandwidth while retaining the same quality.
This will not affect what kinds of files you upload; only the scaled transcoded output files used for playback will change. All modern browsers that support VP8 support VP9 as well, and our player shim for Safari and IE will continue to work.
All the details: https://www.mediawiki.org/wiki/Extension:TimedMediaHandler/VP9_transition
Comments and questions welcome!
-- brion