Call off your patent-trolling dogs and maybe I'll code to your closed, putrescent platform.
You know I don't know why they don't just project an infrared image with the cinema's name on it on the same screen as the movie. Standard cameras will pick it up, but the human eye will miss it entirely.
OR how about three IR leds and a fourth one on a post sticking out from the top of the screen? That three dimentionpattern should give you the precise seat location of the pirate.
This technique, and all techniques fail IN CINEMAS WHICH DON'T IMPLEMENT THE TECH!