Hey, look what I found while Google searching for specifications to create YouTube channel banners (not the paid banner ads, but the branded banners that appear on the top of customized brand channels or partner homepages).
A lot of this applies only to “branded channels,” but it’s still more informative than the meager YouTube help section.
Not sure if this was a fluke or if it’s supposed to be public… Hey, YouTube/Google. You want these pulled down and I’ll do it. A Google t-shirt would expedite this request to our level 1 web support.
Here’s one for running contests: