I would of looked into minimising the movie being played, and looked for proof there were more than a single film on there. And then possibly got the police involved.
Would be interesting to know if the store is still displaying this, or other divx/xvid's on there.
How would showing a crappy xvid rip show of the fancy high res screen that can probably display bluray content (or atlest HDDVD/Blueray rips)