HTML5-video - autoplay

HTML

<video autobuffer controls>
  <source id="mp4" src="http://grochtdreis.de/fuer-jsfiddle/video/sintel_trailer-480.mp4" type="video/mp4">
</video>

CSS

video {
    position: fixed; right: 0; bottom: 0;
    max-width: 100%; min-height: 100%;
    width: auto; height: auto; z-index: -100;
    background: url(polina.jpg) no-repeat;
    background-size: cover;
}