Firefox 4 nightly builds just got support for WebM, the recently announced open video format, based on Google’s VP8 codec.
Previously, WebM support was only available in experimental Firefox builds that debuted the day WebM was announced, a few weeks ago.
Recently, Google announced a change to the WebM license to address some concerns about losing all rights to the WebM codec code, instead of just the patent license in case Google got sued for violating some submarine patent.
It should become generally available with the first Firefox 4 beta targeted for late June.
More details on the landing in Chris Pearce’ blog.