I guess that depends on your definition of TMA... Danzan Ryu has a list of gun disarms. The Shotokan Karate I studied, had their list of gun disarms... though I am not sure how codified that is in Shotokan. However, the concepts that are used in the gun disarms are simply principles and ideas that are taught in the system itself, used in a different context.
There is quite a bit of difference between what was demonstrated and what you are showing in the Fairbarn footage. In the Fairbarn footage, the guy's first move is turning to get offline, while entering... once he gets in and has control of the arm, he immediately takes the attacker down. Your guy's first move is to push back into the gun... I did not listen to the audio and don't know what he is saying about it... but when you watch him, his back suddenly presses into the gun before he rotates. That impulse into the gun can many times cause the other guy to pull the trigger in response... been there, done that with simunition guns... if you impulse back into the gun I am holding, you get shot, point blank in the back.... if you roll offline, without pressing back into the gun, you get much farther offline before I can react and pull the trigger... the difference here is subtle, but important. Your guy then makes no attempt to take the guy down, he relies on his "unbreakable" control of the arm, to keep punching him in the face.... if he slips out, your guy is directly in front of the gun barrel.
As for the disarms from the front... he only goes for a quarter turn to get offline, and does not even get that far when he moves. Further, he stays in front of the gun, instead of getting inside the gun... again, if he loses any control at all of the gun, he is immediately in front of the barrel. Further, his other hand immediately goes right in front of the barrel... which is a good way to get your hand / arm shot. Some time with simunition or airsoft will quickly show how often waving that hand across the barrel will get it shot.
One of the things that the Fairbarn guy does, is that as he turns offline, he enters inside the gun and gets close to the other guy. If he loses control of the arm, the other guy still has to make space and or maneuver to bring the barrel of the gun back on him. This is absent in your guys demo. So, while it is similar, it is not the same thing. Regardless of what he is teaching off camera, he is not demonstrating those things while on camera...