Scanning Device On IPhones, What does it do?

My family was recently having a garage sale, there was a man who came in with a I phone looking devise and scanned all of our Playsation Games, DS Games and CDs. The devise had something plugged into it, it was a small black box and it had a red light, that he was scanning things with. The man did not look at his phone in between which we thought cancelled out looking at the worth of the item, He was very very quickly scanning and he also did not by anything and walked out the second he had finshed. Can anyone tell me what he was doing? My whole family is very curious.