If we ever head down the path of concealed carry (and sincerely hope we do not) I will be the first to sign up - no point bringing a knife to a gun fight. Problem that was highlighted in the video posted was that you can't predict a surprise attack. How do have a finger on the trigger and carry your groceries or ride your bike or hold your kid's hand when you walk down the street etc etc? I was a competitive kick-boxer in my younger days, I have a mildly anxious predisposition and am hypervigilant when out in public - tough to be more 'situationally aware' (read fearful) than me - been knocked out twice when hit from behind. (and using fearful is not meant to offend - fear is a natural human response to threat or perceived threat and without it we would likely be hurt, so it actually acts to keep us safe).
Just so there is no confusion, I'm not anti-gun, quite the opposite. I'm just more about addressing social inequality, repression, and disenfranchisement such that minorities or the otherwise marginalised have some prospect of a 'better' future - give people something to lose (e.g a prosperous future) and they will generally behave themselves.
With nothing to lose - put a sign up on grandma's lawn that she's packing and I'll simply shoot first, steal second. America has had the right to bear arms since forever - has the average rate of violent crime increased, decreased or remained static in that time?