I thought you were supposed to take the pictures after you scratch the car, so that you can "prove" that the damage was there before you picked it up.

My point being, what are photos or videos supposed to prove. If the car is damaged before you pick it up, and there's some reason that you are still taking it, then you should get the agency to sign something attesting to it.

Oh, that's only if there's a borderline case. I.e. if there's something you didn't really see when checking yourself (nor remember), but can find in the pictures later, if necessary.