Another Method (Score 1)

Why don't they play the movies at different refresh rate. Just like a when you record a computer monitor with a video camera, you see black line crossing the video every once in a while. This is because the refresh rate of the computer monitor exceeds the refresh rate of the video tape recoder. Remember the Nyquist-Shannon sampling theorem? If they go faster, the human eye won't see a difference, but the cam will record the annoying line.