I was visiting our local (Eugene, OR) Jack-in-the-Box and noticed a sign that said, "This Premise Under Video Surveillance." As far as I know, a premise is a proposition supporting or helping to support a conclusion.
She's correct, of course. Premises is a plural noun that means building, part of a building, or in a legal context, "things stated at the beginning."
Sigh. This is what happens when people dig into their fancy-Latin-word bag and pull out the wrong thing. What's so bad about saying "This restaurant is under video surveillance"? Or even "You are being videotaped." Either is going to be more clear to the people who most need it: the sadsacks who can't figure out how to behave in a fast-food joint.
Still, we would like a video camera that would examine premises--the plural form of the singular noun premise. It would be nice if a camera let us know when someone, a politician, maybe? is making a bad argument.