Don,
I think Graham has the answer - talk to the restaurant owner about it and see if he can put a stop to it. I had a similar thing happen to me and it is costing me jobs at a place. They recorded using very good camera equipment three of my gigs. Months later I seemed to never get calls from them - well , they use the videos instead of hiring me. I ran into several residents from this place and they all confirmed what I now know is going on.

Anyway, I would talk with the owner of the restaurant and have him put a stop to it.

Deane