One thing on the video, shouldn't lower the hammer down from half-cock without pulling it back to cock and then lowering the hammer. Otherwise the bolt may not drop completely out of the way and cause that scoring around the cylinder you pointed out.
It wasn't clear whether you had replaced the hand, - if you had it may be a tad too long and need to be dressed back to prevent it from over indexing?
I doubt if the cylinder is at fault, so I wouldn't think there's a need to replace it. Especially since it was working well before. It did not appear to have excessively free spin from the video when on half cock. My suspicion is that when disassembled, you cleaned the cylinder arbor and slot and oiled it, hence smoother rotation. When at half cock, nothing engages the cylinder so it is free to spin against hand. Is it possible the hand spring got compressed a bit and isn't giving positive force to engage the cylinder hand notches fully?
If your tinkering has not corrected the problem, turn it over to a gunsmith to look at before spending money on parts. He/she will better determine whether you need replacement parts, and which ones.