I checked out the video URL in the Gunbroker listing, and immediately recognized the guy in the video:
And there are at least two more on the Beta Pattern Muzzleloader.
The man who designed and began building these is a talented guy with an inquisitive mind, a wide variety of interests, and a YouTube channel called "TheIdahoanShow." He does a lot of imaginative work and experimentation in gun building, barrel rifling, ballistics, metal working, etc.
The channel is pretty interesting, in my opinion.