But that's the mystery, it wasn't a motion picture, it was a filmstrip in a little white holder and it would automatically advance along with the tape. I remember the brand being Audix or something like that.
I also remember a weird av thingy made by Hoffman. It had its own screen and it used a 45rpm record and a strip of film (kinda like a GE Show and Tell record/film viewer. You stuck the record into the slot, flipped a lever and watch the show.