I have a video clip of falling leaves, in which I'm trying to isolate a single leaf for use elsewhere. I'm doing this by creating an opcacity mask, outlining a path for that single leaf. Because it changes shape as it falls, I have manually adjusted the mask frame by frame. When I go back, the frames are distorted and incorrect, not outlining the leaf. I have now done this twice. What am I doing to cause this to distort over and over??