drawVideo method

Hi!

I'm planning to use this with diaporama to make an interesting slideshow on a client's website. One thing I'd like to do is have a slide with a tiled, looping video background.

I'm thinking I can extend the canvas api as you have done with `drawImage` - I'll probably have some params to control sources, framerate etc. Do you have any thoughts on this?

I'll update you on my progress anyway.

Thanks for both projects btw, awesome work.

James