Does anyone know of any free (or inexpensive) graphical editing packages that include green screen type editing, preferably for both still pictures and video, but green screen editing for video is my main need. My son wants to buy the Rip Roar Creation Station for this but I've read that' its pretty bad. He has a Flip Ultra HD video camera and would like to do green screen editing with that. I know I could get my own green screen or just get the right colored sheet for the "green screen", but I need the software.

Thanks!
Larry