I found this tutorial on how to do difference masking. it's a lot of work for a simple effect. is there a plugin that does the same?
No, the tutorial example is complicated, difference masking is a simple, two-click setting.
1. Click track composite button
2. Click "Difference"
3. Done.
That's all the instruction you need to get started. Good luck.
I'm not in front of computer at moment but if I have 1 track as background without presenter, and 2nd track with presenter i can get same effect as chromakey by only doing as you have described to separate presenter from background?
I don't think so, compositing involves transparency, Chromakey involves solid layers.
But when you're at a computer, do show us a screenshot of what you want to do.