As a matter of fact, I did see three of these about two weeks ago at a local gun show. They were antiques but the dealer who had them, is in the process of manufacturing them, or so he said. Seems that there is a lot involved with legally making and marketing them. Did not pay all that much attention but I believe the ones I saw, were M/L's. up until a few weeks back, was not aware that they existed.. ...
As in that video, he never showed how it was loaded, but it looks like you un-screw the front screw out provided in the box to remove the cylinder to load.
I have a book of odd guns and you'd be surprised at what type have been made. Tobacco pipe, belt buckle, Zippo, a glove that when you punched someone it shot them too, etc...
Those glove guns were developed during World War II for Seabees working on formerly Japanese occupied islands in the Pacific.
Theory was that if a Japanese soldier tried to get up onto the equipment that the Seabee was operating, he'd land a punch and the mechanism would fire a .38 Smith & Wesson round into the enemy.
In theory, great. In practice, not so much. Too bulky. It was easier just to assign a couple of armed guards.