After using videojs initial fixed-width or height to the <video> write fixed width and height, in full screen mode causes the video to expand in the upper left corner, before writing to maintain a given width and height, but no true full screen.
If JS by changing the width and height of the video in full-screen after clicking the button, you need access to videojs documentation, implementation is more complex (the reason is too much food).
In fact, full-screen by CSS is the most convenient, only one <div class = "videoWrap"> in the video external units,
Then the desired width of the original written in the high videoWrap, for <video> We just give a {width: 100%}, no need to write a predetermined height.
This will not occur because the <video> write fixed-width high and lead to full-screen can not really covered screen.