HTML5 video is a hot topic. The idea: make the process of embedding video as easy as embedding images in web pages. The markup is simple, but there is a real challenge with video encoding. MP4/H.264 or WebM? FLV? WMV? The jurry is out, but today there is one format that has the farthest native reach: MP4/H.264.
This codec/container pair is support on iOS, Android (today), IE9, Silverlight, Flash.