General Public. I believe the type that is most common were called Mutoscopes, made and marketed by International Mutoscope co,. and mostly crank operated. they were once a fixture in amusement arcades/ Turning the crank flipped the cards and produced the movie effect. a more sophisticated motor-driven type was used in the more sophisticated arcades and these often were shorts of boxing matches such as Sugar Ray Robinson, etc. These machines, both types survived well into the sixties and seventies as a sort of nostalgia-= rerun thing.