It used to be routine for old black and white films to be shown at the wrong speed on television simply because they were shot at fewer frames per second than the broadcast standard 24fps - resulting in the jerky presentation we used to get. Digital processing allows "extra" frames (duplicate or interpolated transitory frames) to be inserted, allowing these films to be seen as they would have been on older, matching equipment.

Could it just be that no-one registered the recording speed of the original equipment? Was there even a standard speed then?

Ross