With Tracker2Mask you can track the movement of masks using the After Effects tracker. Just track a point and Tracker2Mask moves the mask accordingly. You can also track several points within the mask area to improve the result. For rotoscoping tasks, Tracker2Mask provides some handy extra functions that allow for a tracker-assisted rotoscoping workflow directly in After Effects.
I want to personally thank you for saving me from countless hours of Roto-Hell.
I don't know how I'd live without this script. I use it every day.
What a brilliant time saver. Thanks Mathias. And thanks for the great tutorial.