Late for his flight, a Delta Air Lines passenger began banging on the door at his boarding gate in New Orleans. Perhaps he did not realize that when this door is closed there’s literally no one on the other side of it to open it back up. Pounding on the door won’t get a staffer’s attention.
Once the door is closed it is highly unlikely to be re-opened. You need a gate agent, and it’s only the rarest circumstances that anything can or will be done. This man wasn’t giving up, though.