So, I finally watched this show last night. I am not sure if I totally buy that those are the Regulators, but it was all pretty intriguing. Correct me if I am wrong, but the guy who found the tintype convinced the 2 guys at the end that it was in fact the Regulators/Billy. They paid him 5 million for the tintype and are now hoping to sell it for more.
One thing that makes me dubious is that we haven't already heard about the picture selling for more. I figure there would be collectors falling all over themselves for that piece of history. Maybe the 2 guys agreed not to resell it until after the show aired, and they still have to arrange for an auction.
The one thing that I wish they would have delved into further was how they determined that the topography matched that spot on Tunstall's ranch. If they can definitively say that the pic was taken in that location, and the guy who verified that the technology matched what was used for that 10 year period, then I would agree that there were enough similarities in appearance of those people, and images of other key members of Billy's posse that the people they identified are probably who they are saying they are.
p.s. I have seen Young Guns, and other versions of the life of Billy the Kid. I could have done without all of the reenactment parts of the show. It was twice as long as it needed to be.