Ah, I understand. This should be a lot simpler now. Thanks.
Also this should have been my first question, but how exactly do I use the mask effect? When I apply the mask I have this giant black void around it and I get this permanent image echo effect for anything that moves around in the black.
And is there a way to invert the mask?
Edit: If I make the mask dynamic (having it move) it acts like a paint brush, undoing the rest of the mask. (that's not really my goal)