My local gun store just recently installed an extensive video security system whereby there are five or six video cameras positioned throughout the store. You can see yourself on screen in every corner of the store, as can the staff. I assume it's all recorded, too. I also assume that it auto deletes after some hours or days, but it could easily be used to get a face shot of everyone who buys a gun.
The cameras may be to deter people from stealing magazines, bolts and other gun parts and accessories.
