I am checking on the feasibility of this project. I would like to have to videos side by side. I would transform the shape of each video into a negative sloping line on the left and a positive slope on the right to make a V. When a viewer walks past the video, that part of the V would follow them. If the viewer was walking right to left, the left leg would follow their movement. The opposite for the other direction.
My set up would be 1 computer to process the video and 2 PIR sensors to detect motion for each screen. The computer would be hooked up to a video hub with 2 projectors.
Would I need 2 arduinos and 2 sensors? Would it be possible with 1 arduino and 1 sensor or could I put 2 sensors on one arduino?
I briefly played around with the PIR sensor from Parallax. It was very sensitive to at least 6 meters from the sensor and at least 5 meters side-to-side. I suspect the cone where a PIR sensor fires may be too big to get what you want. You may be able to shield the PIR sensors for better results than I had (think sensor inside a toilet paper roll).
I also briefly played around with a distance (ping) sensor and decided that will probably work better. The one I tested was sensitive in a fairly narrow band. The idea is: if there is an object straight ahead within about four feet, a human is there.
But, in my case, I just need to know if there is human standing there. I don't need direction or motion.
In either case, I would appreciate if you report back with your results about human sensing. If you'd like, I'd be happy to do the same.