Obvious answer would be darker colors. Makes the video "pop" more and your eyes focus on the screen and not the room.
Good line of thought is to picture a movie theater. It is dark with dark colors.
I've seen a lot of black and dark grey, but those were in dedicated theaters. (Except for Sirquack's.) If you are using this as a multipurpose area, you will probably want some color.
Dark blues and reds (maroon, etc) are popular, as are the occasional green and purple.
A lot of it comes down to pursonal choice.
Flat paint is better to keep light reflection down, but of course is harder to clean up than a semi-gloss, so if you have kids that will be in the area, that might be a factor.
Hope that this gets you started.
