When you track a mask with After Effects' mask tracker, it contains lots of keyframes such that it is almost impossible to modify it afterwards. In this tutorial you learn a quick and simple technique to modify such masks with the help of the name your own price extension KeyTweak.
The technique is both powerful and easy: You can simply modify a few keyframes by hand and KeyTweak modifies all other keyframes automatically accordingly.
The mask tracker usually gives pretty good results, but often they are not 100% accurate. The technique shown here is really useful to correct such masks to make your rotoscoping 100% accurate.