That's dangerous, not funny.
I can understand how a guy might get distracted in front of an audience. For example, I'm a great driver, but sure-as-shooting, the moment when I'm trying to teach my teen age kids something while driving is the most likely moment I'm likely to make a stupid driving mistake.
That said, knowing how to "safe" a weapon before turning it over to someone else is "weapons training" 101. I taught my son how to do this when he was seven or eight yeas old - if he found any sort of semi-auto, he'd know how to drop the mag, clear the chamber, lock open the slide, and turn it in to an authority.
Perhaps this guy was trying to explain that a semi-auto "could" have a round in the chamber, and still be "loaded" even if the mag is removed. But still, anyone who's had handgun training should know better than TAKE A LOADED HANDGUN to such a demonstration. There are inert, practice rounds that can be used for dry-firing; he should have taken a half dozen of those things.
There was an rookie officer shot and killed - maybe this is 10 years ago now, in Southern California when his training officer and he were stopped in a parking lot, using "unloaded" weapons to simulate a care stop. I guess the training officer was correcting the new cop's on-the-job errors. The guy should have cleared and safed both weapons, or even had practice weapons in his car for that purpose. A stupid error killed the rookie.
It's just amazing and sad that these things still happen. I can recall one incident when I was firing with my son (then about 12 years old) at a range. The range rules (or at least my military training) dictate that no weapon leave the firing line loaded. I was putting away the weapons we had out, and one that my son had been firing, and I moved the weapon from the firing line to a table in the rear area to put it away. When I opened it, I found out it was loaded. I didn't realize my son had reloaded it and left it on the firing-line platform. No one but I knew of my error, and it was no where near lethal (you have to make about a half dozen handling errors to actually discharge a weapon in error; I only made one.), but it was such a stupid mistake that I still kick myself over it. I should have cleared and safed the weapon as soon as I picked it up; never made that mistake again. No matter when or where I pick up a weapons, if the slide is not already open, I check it, and lock it open before moving anywhere with it.
SFS