I'm not a fan of the guy at all, but the airgun thing is a little hyped.
He was using a Wingun SAA that had originally been converted to airsoft, which requires 3 parts changing. Shells, barrel, forcing cone.
The airsoft and the airgun SAAs, and indeed the same is true of the Dan wesson, chiappa and the schofields, are exactly the same in terms of parts and power. That's why they're not site legal unless you drop some power down shells in there. They all come off the same Wingun line.
The guy that sold him his, fitted it with a homemade adjustable hop, power down shells and was site legal. I think he claimed it was provided by some airsoft site overseas which was a lie.
The airguns outnumber the airsoft versions by about 10 to 1 it seems so more than you think get converted this way for people who play theme games.