I used to be in security (loss prevention, etc).
I used to catch people all the time and every once in a while they would ask why I was even watching them in the first place AFTER I already caught them stealing. That's when I tell them I already saw them steal a week ago on camera, I had been waiting on them to come back.
It's very possible the person recording him saw him do it already and waited for him to do it again.
