I had one. Loved it.
There was a 7" record that was played at 33 1/2 rpms and there was a film strip in a rigid plastic viewing case, probably 1.5" by 8 or 10". On one side of the strip were corrugations that fit into the gears inside the machine.
You slide the strip all the way down into a slot at the top right of the machine and start the record. Using a light, lens and reflective mirrors, the image on the film strip is projected onto the screen. Somehow, the film strip was advanced on its own by a motor. It wasn't magically prompted by the sound; either it was on its own timer or was triggered after a certain number of turntable revolutions. As the song or lesson played, the strip advanced along, slowly creeping up and out of the machine, often out of que or sequence with the record. You could watch the film strip without the record, or just use the record player by itself.
The one record/strip I remember is the day of the week one. "This is the day we wash the clothes, wash the clothes, wash the clothes . . . The machine washes the clothes." A cartoon of a wringer. I think this may have been an attempt at English/Spanish lessons. This was also a good one for the machine, because each verse for each day of the week took the same amount of time and it was easy to sync the strip to the record.
The B-sides to the records were usually good too, having some piece of classical music. This is were I first heard "The Hall of the Mountain King". My sisters did a play to this creepy song, about two little girls with sick hearts, who went to play in a grave yard, until the zombies came out of the ground and they had heart attacks, died and were dragged down into the graves.