As an engineer, I grimace when watching such poorly conceived experiments. I'm very glad to see that all of the faults were noticed by everyone else in the posts above and on the youtube comments section. At least they were obvious faults.

Additionally, as people here have pointed out, the conclusion they seem to want you to reach is to just give up?

In a "real" situation, the shooter would have no idea who is armed. In fact, they wouldn't know if anybody was armed. When the shooter starts, the ensuing confusion and panic will distract his attention to body masses going everywhere. If one person in that crowd draws a concealed weapon properly, the shooter won't see it until it comes to bear. Will the ccw holder stop the shooter? Maybe, maybe not. But here's the deal; I'd rather have a chance to walk away than to be defenseless. Without a gun, my only chance of survival is to hope the shooter doesn't choose me randomly in the crowd.

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"... shall not be infringed."