feature: status: use tags: polyfill gtie8 kind: html polyfillurls: mediaelementjs
Do note you need to supply your video in various formats to cater to all browsers and fallbacks—Miro Video Converter makes this trivial. H264 and WebM cover all browsers (except Firefox 3.6 which needs Ogg Theora). Use the above polyfill or gracefully handle all cases without any scripting, as explained by Kroc Camen in Video for Everybody.
There is also an incredibly useful service called vid.ly which converts video online into all necessary formats and provides a short url that detects your browser/hardware and sends the correct format. Archive.org also converts MP4 videos uploaded to OGG automatically, and does the same with audio.