Commons uses the freely-licensed
Ogg and WebM formats for media files; unfortunately these are not supported by default in Safari and Internet Explorer, as Apple and Microsoft favor a competing format. Manual codec installation goes against modern user expectations, and isn't possible in some environments.
I've spent some research time working on
ogv.js, which uses Mozilla's
emscripten and Adobe's
CrossBridge to cross-compile the Ogg Vorbis and Theora codecs to JavaScript and Flash. This allows decoding and playing Ogg media in the browser without additional software installation.
On Firefox, Chrome, or Opera you'll continue to get native Ogg or WebM playback; on Safari 6.1/7 and iOS 7 Mobile Safari you get the JavaScript Ogg player, and on IE 9/10/11 you get the Flash Ogg player. (Microsoft lists Web Audio as "
in development" for future IE versions, which will enable use of the pure JS version there as well.)
This is very much a work in progress, but I'm pretty confident this is something we can deploy later this year to get basic A/V playback to "just work" for another chunk of our users.
I'll be presenting some further status updates & related topics at my Wikimania talk.
Note that the Flash code used for IE is entirely open-source and uses none of the proprietary multimedia codecs built into Flash. I consider this a delightfully subversive use of Flash, and it would please me no end to get it deployed on Wikimedia. :)
-- brion