I can't view that video here, but I have seen it before.
I think the point they were trying to make was that any single weapon could easily be smuggled in undetected if no search and detection was involved (pat down, metal detector, etc). If a kid has a stash somewhere on the school campus (behind a locker, in a closet, etc), he could bring them in one at a time for a week.
Do you have to be a certain age to purchase concealed carry holsters?
jmm