http://www.html5-fullscreen-video.com/
http://stackoverflow.com/questions/3899865/can-you-display-html5-video-as-a-full-screen-background
jquery plugin : http://syddev.com/jquery.videoBG/

http://videojs.com/
: multiple plugin :http://extensions.joomla.org/extensions/multimedia/multimedia-players/video-players-a-gallery/14836

exemple probant : http://lab.victorcoulon.fr/javascript/video-background/

code source : http://forrst.com/posts/Background_video_with_HTML5-5Xf