Chris Double has announced the implementation of the <video> and <audio> tags for Firefox as defined in the current HTML 5 Draft, currently in development by the WHAT WG (Web Hypertext Application Technology Working Group).
Right now and for its first iteration, support will be limited to Theora and Vorbis, a couple of open source video and audio encoding formats respectively, developed by the Xiph.org Foundation, as recommended by the specification but other formats may be supported in the future as well.
Chris’ implementations uses libtheora, a Theora library that adds 100-200KB overhead to Firefox code currently. PortAudio, an open source cross platform API will enable multiplatform audio compatibility.
Native audio and video support is expected to be included in Firefox 3, Chris says, despite it’s not listed in the most current PRD (Product Requirement Document).
No build to try is publicly available yet but a video cast that showcases a web page with embedded video and the very simple HTML code required to make it. Experimental builds may become available soon, he added.