The WebM Project

http://www.webmproject.org/

WebM is an audio-video format designed to provide a royalty-free, open video compression format for use with HTML5 video. The project's development is sponsored by Google.
A WebM file consists of VP8 video and Vorbis audio streams, in a container based on a profile of Matroska.

The project releases WebM related software under a BSD license and all users are granted a worldwide, non-exclusive, no-charge, royalty-free patent license. Despite this, some in the industry have called upon Google to provide indemnification against patent suits.

http://en.wikipedia.org/wiki/Webm

WebM is supported by Mozilla, Opera, Adobe, Google and more than seventy other publishers and software and hardware vendors.