The problem with the video, is they say "muzzleloader" when they (imho) should say, "muzzle loading rifle". Why do I have that objection? I have communicated with folks who claim that if you filled a .75 caliber musket barrel with powder to the muzzle, that those thinner walls would take the pressure (no ball on top), YET none of those with whom I communicated, had ever tried such a feat.
NOW I'd say it's "even money" that a Pedersoli Bess would take the pressure, BUT the walls of that musket barrel are quite a bit thinner than the walls on the rifle used in this video..., and simply claiming without testing that firing that much powder from your Bess "won't do anything to the barrel" is foolishness. In this case with two projectiles, the fellows do a good job of demonstrating it would injure the shooter, no doubt.
LD