Any of the 1858 pattern Remington copies can be swapped out in a few seconds, once they are broken in, and once the user knows how to rotate the cylinder into it's position. I can do it by feel with my Uberti copies in about five seconds (if I am not afraid to drop the old cylinder onto a blanket under my feet... it takes as much time to stow the old cylinder as it does to load the new one). Sadly I don't have a two-compartment cylinder pouch as would be needed to do this rapidly and have a place to put the old one.
I am sure you have seen the scene in Pale Rider where Clint Eastwood does this exact thing?
The key is a double pouch, with one empty compartment to receive the removed cylinder and the other with a prepared cylinder laying in wait. Otherwise you most certainly need three hands, or a pocket that you don't mind getting filthy with black powder residue.
NOBODY as far as I know has ever come up with any historical references to this actually being done though... We all just want to look like Clint.
If I were setting up a shoot for the screen, first... I would not use Pietta, as the barrel markings will be a giveaway if the lighting is not carefully done or if there are any close up shots. I'd use Uberti. Second, I would not hesitate to take said Uberti and stone a few of the surfaces to slick it up for smoothness. A brand new one will be stiff, and a few thousandths of an inch stoned off of the Hand (the part that rotates the cylinder) makes life a lot easier. A little crocus cloth on the arbor and some valve grinding compound spread on the meshing parts and then cycling it a hundred times before cleaning the valve grinding compound out of the thing will fit the moving parts about the same as a decade of hard use...