That was a lot of lead to push through a barrel in a short period. I'd love to see what his target looked like . I 'd also love to know whether he had, through trial and experimentation, came up with a specific ball diameter, powder selection and charge and lube for each cylinder to account for the heat and barrel expansion, and then used the pre-charged cylinders in a specific order? and if he figured out the safe/reliable limit for how many cylinders he could go through at that speed ?
Its a great demonstration of what is possible and one can imagine how effective that approach would be to dissuade an oncoming attack. One or two six-shot salvos would be increasingly worrisome, but after a defender started firing that third cylinder, attackers would have to be deadly serious to keep coming. As noted above, multiple pistols was probably a more likely scenario 150 years ago than one pistol and four matched extra cylinders, but for a person travelling alone, the lattter solution is certainly more portable.