It's a small world, but I wouldn't want to paint it.
So, you've gritted your teeth, girded your loins, and opened up the rotoscoping chapter. There's no way to paint an utterly pretty picture, so to speak, of the task you face: Rotoscoping and paint tools are generally a last resort, employed when there is no other way to fix your matte. Rotoscoping is the art of fixing a shot frame by frame, generally using masks. Cloning and filling using paint tools are variations on this task.
To compound matters, After Effects did not gain its fame as a rotoscoping tool. You can get good results with the program, ...