Thinking about it some more, the exponential relationship between time and position, means that a slowed down film can never simulate low gravity. If the viewer measures acceleration off the screen, then a 1/6 slowdown will work, but it can’t be made to work if the viewer measures position vs time for a fall from different heights.
You could just do it for one moving object by varying the slowdown to suit the object on screen, but its impossible for two objects and totally impossible with technology from 1969, and you’d be making a cartoon anyway.
