Bing team is quite famous for trying different things on Bing Home page. This time they come up with “Video background”. The video background is powered by HTML 5 and currently only available for US users. It should be available in other countries in coming weeks. Some have been comparing it to the "Google Doodles".
To play the video on Bing Home page, Bing has used standard <video> tag of HTML 5.
<video width="956" height="512"autobuffer="true" loop="true" src="/az/hprichv/?p=GlacierMtTL_Wilderness_TL2.webm"></video>
Bing home page contains video clip in at least three different formats – webm, mp4 and ogg and it plays the video according to the browser and thus the clip should play just fine in any modern browser including IE and Safari.
Evolution of the Bing Homepage