One of the things we've started doing at work is creating short how-to videos and updates for our website. For the first video, we used a black sheet as a background... it surprisingly turned out quite nicely, but it was definitely not a permanent solution!
So I thought about it for a little while and came up with a super awesome (and cheap!) solution that I have to say I'm pretty damn proud of. I found an outdoor fabric from Fabricville that doesn't wrinkle, and is quite rigid. I sewed the top and bottom onto fabric poles, and added grommets to either end to stretch. We re-used an old banner support and voila! Awesome video backdrop!