Camera film - the sort of thing Kodak sold before it went out of business - resembled a strip of hard plastic. It consisted of a series of stills that you could spool onto a reel. If you viewed them at speed, say 24 per second, you created the illusion of motion. Hence: 'moving pictures' or 'movie'.
If you decrease the rate - as for a cheaply-produced cartoon - the illusion suffers; the action becomes jerky. To improve the effect, you increasing the frame rate.
Since a movie is linear, it has a start and an end (with an occasional unintended break when the celluloid melts). But what if the filmstrip had two dimensions? What if it was a film-plane? What if your projector were able to spool or scroll the film sideways or diagonally?
You would potentially be able to select from a set of alternate stories.
An even better, more up-to-date analogy is Google Earth. Here, you have a gallery of film frames that you get to transverse and follow the roads where they branch and intersect.
Come to think of it, any virtual reality game would do the trick also.
