Count me among the confused with these videos.
While the makery is very clever, all they seem to show is that very dedicated, creative individual can come up with come absolutely shitty weapons even with the TSA security precautions. A grenade where the user demonstrating the destructive power takes cover behind a blast shield of corrugated cardboard? Change point blank through drywall at 260 fps? So, as dangerous as a recreational paintball gun, except to the person using it. Great. What is the purpose of break action loading on a weapon that pretty clearly destroys itself after a single shot and likely disable the hands of a user I wonder?
If anything, it reinforces the fact that security theater apparently works, because this is the best a dedicated, creative individual could do.
Of course, none of it is as scary as an able bodied adult screaming and swinging a chair from the food court.