Full Page Background Video Styles
I bet you’ve seen it. A video background that takes up the entire browser window. There is text on top of it (hence, “background”), which is an interesting effect that you don’t see every day. The biggest reason you don’t, probably, is that you can’t set a movie file as the
background-image
in CSS. You’ll have to do some layout trickery to get it done.
Source: http://mediatemple.net/blog/tips/full-page-background-video-styles/