If you watch the video again, you will not see one Ram Rod pulled and ran down the barrel of a gun, except the cannons. All gun barrels are pointed up to an obvious "over the head shot". Safety is foremost. If someone would pull his ram rod, the other side would start shouting about it. If you have never shot a muzzle loader, you have to use the ram rod to get your bullet down, unless it was a much smaller bullet than the bore.Powder build up would probably stop it before it got midway down resulting in a squibb load effect.

Squibb load is when you don't have enough powder to propell the bullet out of the barrel or just far enough to exit the barrel and fall to the ground. Not to mention a small bullet would lose accuracy and muzzel compression which would lose muzzle velocity.

Chances of a real bullet are real small, but not impossible