First, read up on how old film projectors work. It’ll give you a clearer picture than I can explain. Old film are not magnetic information stored on strips, nor are they hole burned into plastic. Old films are a series of quickly taken photos unto a photo film strip. Imagine current day burst shot of digital cameras. Each photo taken is called a frame on the film. Ever taken a look at a developed film negative? It looks the same. Each time light passes through the frame it projects the image unto the surface the light lands on (board, wall, etc). If the light is constant, you will see a whoosh movement in the direction of the film movement. To create image after image on the screen to simulate, the projection is strobed. Our eyes capture light at about 60Hz (is I remember correctly). Old film projectors produce a strobe of flickering light at about 48Hz or so, passing through the film. The really old ones are hand driven, so the speed depends on the operator. This is also why old film