I had a requirement to add full screen capability to shadowbox which I thought I would share (could possibly be a 3.0.4 version?). It works in all latest browsers that support it (IE11, Chrome, Firefox). It has an option available to turn the feature on:
It defaults to false.
One of the killer features for HTML5 video is native browser full screen support. Without it, a viewer watching video through HTML5 is limited to seeing the video within the browser window, which is clearly not an immersive experience.