Chris Double writes, “The patches to add support for the WHATWG video and audio elements has been applied to the Firefox mozilla-central repository. This means you can get the source for Firefox and build it with support for <video> and <audio> by using the configure flag ‘–enable-media’. The patch that landed does not yet include a backend decoder. It won’t play any videos as a result. That will be fixed when the various backends are landed.” For more information, see Chris’ weblog post.