Well, before everybody had frame interpolation, early 16FPS film tended to be copied to new film run at 24FPS. There were horrible hacks like "3-2 pulldown", to convert 24FPS film to 30 FPS TV. (30 FPS TV is 60 interlaced half-frames, so one 24FPS frame was shown for 3 half frames, then the next for 2 half-frames. This was done mechanically in the projector. Then that got copied to VHS...