The point the guy is trying to make (but not articulating very well) is that a shotgun isn't going to blast a 45 degree radius cloud of death that cuts your assailant in half, even at close range.
When shooting a shotgun at long distances and moving targets...you put the front bead on the target with both eyes open - effectively "pointing" instead of aiming - then abruptly slap the trigger, continuing to track the target (follow-through).
When shooting a shotgun at shorter distances, with buckshot (a typical defensive scenario), you can aim it more like a rifle, and will get about a 6 inch spread as shown in the video. But it's also worth noting that if you point properly, ie "get a bead on" your target, you should get the same result.
It's worth noting that the diameter of each #00 buckshot pellet is .330 inches, and there are 8 of them in a standard 12 gauge shotshell. So one blast from a 12 gauge loaded with #00 is about the same as emptying an 8-round magazine of a .380 into your target. THAT is why shotguns are ideal tools for home defense.