I saw the same video, and thought the same thing. However, the fish in the video are Rio Tepic fish while the fish for sale are "Rio Valuarte". I can't find a good map though, it is possible that the two rivers join somewhere.
interesting...might be legit might not...until someone tries to see what they get is the only way to find out...unless he actually has proof of it...he needs to show pics of the fry's since thats what he is selling not the big ones