[youtube.com...]

I did test out a few things though.

I noticed that you could update the background colour of the boxes and headings, so I figured you might be able to slip a url(http://myurl.com/image.jpg).....

Unfortunately even if you manage to make the declaration within the 30 characters you've got available, it still doesn't hold the value.

Start off with a background image that looks great across different screen resolutions, wait until you have a strong following of viewers and then approach youtube to become a partner.

Goodluck.