What cartridge is that Henry firing?
.45 ACP? .45 long? .45-70?
Based on the vid, I am suspecting the Long Colt, but can't be sure.
Late Add:
Also, I noticed that in every instance I could see, all shooters dismounted the rifle in order to cycle the action. That seems odd. Especially in the fact that you're chambering a new cartridge and the muzzle is swinging in an arc and not consistently pointed downrange. Not that it is my place to lecture anyone, but I would ask if there is/was a reason to not reload/lever while keeping the rifle shouldered.
English
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We were firing the .45 Colt. We're practically out in the middle of nowhere and we never touched the trigger until we were ready to fire. I assure you, we were being safe.