Its hard to find a better quality background. I tried to do it for 27" display and couldn't find one too fill the whole space on the page. When you use a background that's too small just darken the sides and make the background color black for a smooth transition between your background and youtubes.

Thats definitely the best thing you can do, a lot of the time when designing for huge monitors you will find that its almost impossible to fill all of it and you end up losing quality in the end for adding more to it.