[Tim Byer] “What if I have someone walk in front of the screen during the video? I would need a green screen at that point and time right?”
—-Yes, you would. Or you could rotoscope, but that’s always a pain. Greenscreen would be better. The tricky part is that you will lose the corner reference when the person is blocking the corner (if they walk in front), and have to interpolate the position during those frames. BTW, green (or blue) fabric or cloth cut to fit will generally work MUCH better than sending a signal (color image) to the monitor.
-jeff