Whoahh read what i said, they won't refuse the insurers they will however need a letter from a lawyer will get it. I would doubt they would hand someone off the street a copy of their footage. I certainly never handed out a copy of footage in 12 years of doing it to any member of the public. I did however hand hundreds of copies to the police and appeared in court some 15 times to say so.
I would however bend over backwards to help customers in your situation, i could usually give make/model/colour/registration occupants description, any distinguishing features of the car. If the police got involved there are other types of info you can hand out to identify them.
You will probably need it in formal writing of legal nature to the operator of the forecourt to get an actual copy. But the staff should give you the details of the car and owner, if not get the police involved a clever petrol manager will bend over backwards to help the police, the old you scratch my back situation.
Your insurance company should deal with all that crap anyway, all you need is the reg and brief description.
The main reason companies had such anal policies about footage is not for any personal privacy or secret information (you can isolate individual cameras so not to show sensitive info) its simpler than that, if dodgy people know where the cameras are pointing and the quality of each of the cameras it becomes a security issue. People intent of driving off will avoid cameras at all costs so protecting where it really looks is quite important. And the housing doesnt always show where the camera is pointing! or which housing has the high def cameras.
Under the data protection act individuals have a right to request all footage and images where they are featured.