Some good advice from Matthew.
The trickiest removes are when the back ground is changing in every frame such as leaves blowing in the wind. In these scenarios it is very difficult to have an automatic solution and is usually accomplished by combining a couple techniques: clone, paint, patch, etc.
If the clean frames do not exist within the shot, you need to create some clean plates.
Sometimes it is simply a time saver to use Remove Module to get you 80% there, than fix the remove with patches. It all depends on the shot. Other times, you might want to consider using the mocha data to stabilize the focused area, do your paint/clone fixes, add motion back in. mochaImport+ script for AE is quite useful for this.
Best,
Ross
Ross Shain
Imagineer Systems
http://www.imagineersystems.com