The problem that you’ll find is that when you record from Camtasia, you really don’t want to reduce the size or people won’t be able to see anything.
DVD video is 720 x 480, so if you could capture only that size and keep the same size for your video, then it should show up fairly well.
I’d experiment with frames per second.
I think their standard is 15, which should be fine for most captured demonstrations.