Masking

There are third party tools, up to 50 points. I can't make any of the silly masking tools in FCP work properly because of the weird interfaces and the discrepnecies between what happens in the viewr and the canvas. I go to Motion for any serious hand-masking jobs.

bogiesan

Paul Crisp makes a series of garbage mattes up to 64 points. Yes, they're a bit arcane, but they work when you want to keep it all in the time line.

Why did Apple only provide up to 8-point mattes? Probably because it serves 90% of the need and they knew about Paul Crisp.

If you are going to be keying movement of the mask, do yourself a favor and use Motion...