Html5 Full screen video

No, there is no way to do this yet. I wish they add a future like this in browsers.

EDIT:

Now there is a Full Screen API for the web You can requestFullscreen on an Video or Canvas element to ask user to give you permisions and make it full screen.

Let's consider this element:

<video controls id="myvideo">
  <source src="somevideo.webm"></source>
  <source src="somevideo.mp4"></source>
</video>

We can put that video into fullscreen mode with script like this:

var elem = document.getElementById("myvideo");
if (elem.requestFullscreen) {
  elem.requestFullscreen();
} else if (elem.mozRequestFullScreen) {
  elem.mozRequestFullScreen();
} else if (elem.webkitRequestFullscreen) {
  elem.webkitRequestFullscreen();
} else if (elem.msRequestFullscreen) { 
  elem.msRequestFullscreen();
}

Full documentation

From CSS

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

All hail HTML5 _/\_

var videoElement = document.getElementById('videoId');    
videoElement.webkitRequestFullScreen();

Here is a very simple way (3 lines of code) using the Fullscreen API and RequestFullscreen method that I used, which is compatible across all popular browsers:

var elem = document.getElementsByTagName('video')[0];
var fullscreen = elem.webkitRequestFullscreen || elem.mozRequestFullScreen || elem.msRequestFullscreen;
fullscreen.call(elem); // bind the 'this' from the video object and instantiate the correct fullscreen method.

For browser compatibility: MDN & Can I use