BigScreen.element needs to check for all <video>s

[bdougherty]

It only checks for the one it knows about called explicitly through request(), but it's possible for a <video> to enter fullscreen automatically when it starts (for example, on the iPhone).

I think the best way is to select all videos when element is called and check each one. That means document[fn.element] should be checked first to avoid unnecessary DOM interaction.

[bdougherty]

Fixed by bf83a10 (made possible by 4c24faf)