Is this a muzzleloader?

[Jack]

I say that's not a muzzleloader.
It is being loaded from the muzzle, true, but it CAN be loaded from the breech. A genuine muzzleloader cannot be loaded from the breech.
As a historical precedent, I'll cite Harry Pope, and the other Scheutzen (sp?) target shooters of the late 1800's. Harry Pope was the premier gunsmith of the target shooting crowd of that era, and his preferred set up was a single shot breechloading rifle. However, the rifles sometimes had false muzzles and the projectile could be loaded from the muzzle. A cartidge, primed and loaded with BP, was loaded from the breech- exactly like the film clip.
Harry Pope's rifles were often loaded from the breech, too. A soft lead bullet was seated into the rifling, separate from a cartridge, with a seating tool. Then a primed and loaded cartridge was placed in the chamber. Voila! breechloader! Just like that guy's AR is a breechloader.
That fellow may be using his AR as a muzzleloader, but you could do that with most modern rifles. If you can load it from the breech, whether you choose to or not, it's a breechloader.