Blender node editor/compositing

Lately, I've been messing around with the Blender node editor. In this short animation, I had my little brother stand in front of a blue tarp while I took a movie of him jumping. Then, in the Blender node editor, I was able to make the background to show through only were the blue tarp was.















Here is the link to the movie:
Jacobjumping.wmv
(He's trying to jump up the hill, I guess.)

Recently I stopped at a fabric store (quite embarrassing) and bought 3 yards of 60" wide, green canvas. I haven't tried it out yet, but I think it will work better than a blue tarp.