When I read the story I wondered how the robber "realized he had forgotten to load the gun". I would think that in the heat of the battle (or in this case the robbery) it just doesn't pop into your head that you forgot something like this.the man realized he had forgotten to load the weapon
In watching the video several times it appears to me that he realized he forgot to load the gun after he pulled the trigger and it didn't go off. Watch the video and see if you see the same thing. It appears that he pulls the trigger while he's waving the gun around and then looks down at the gun to see why it didn't go off. Perhaps I'm wrong but in the story it states:
Perhaps the clerks nonchalant attitude didn't set well with the robber and he planned on firing a round to either get his attention or kill him. Anyway, the clerk is lucky to be alive.He told me to give him all the money," Alam said. "I told him to relax."
Alam stayed cool. The security tape shows him continuing to stock the shelf as he opened the register. As Alam reached for a stack of $20 bills, the man realized he had forgotten to load the weapon and stuffed a shell in the chamber.