I shot some video with a green screen, and it turned out quite good, but I used a circular green screen and in a few shots, the top right corner of the screen was not green. There is movement to the left and below the corner, but nothing intersects the troubled area. I just want to crop it out, but I can't figure the best way to do that. I tried enlarging the whole video which solves the problem but it cuts off some of the actor's head.
What I really need to do is simply crop a corner, not a side. I can't find a simple way to do this. Any advice?