Well first of all the Youtube layout changed, so you can't make it exactly like that one. Now it's more of a large content block with a bit of a border to play with.
I never made a Youtube background before so I'm testing the waters a bit with my own Youtube Channel, figuring things out and such. I'm thinking maybe I should create half of the layout and just mirror it to the other half. Then add some other effects to nix the symmetry.
Right now my layout is this:
http://i.imgur.com/dA8zC.png
And it looks like this:
http://www.youtube.c...er/TheSolartide
I'm thinking the top needs some sort of bar to blend in with the top of the page the start of the content.
Doesn't seem like something you can arbitrarily whip up, will need some planning.