Thanks for everybody's feedback so far. Rather than a bunch of replies, this is to FLS, Latrobe and Joach1M:
IRL I have a civilian pilot's license (single engine land) including some basic aerobatics training in a Great Lakes Biplane. Does that make me a better player in AH...NO!
But what I'm seeing in one version of this maneuver is what I was taught as a Hammerhead Stall. Climb straight up full throttle at about an 80 degree angle, and then just before the stall and still at full throttle kick hard rudder towards the torque pull and the plane will snap around 180 degrees. You can control the stall point by pulling back on your throttle for just a moment, but the rudder kick is at full throttle as you're counting on the torque to snap you around more than the rudder. It is a pretty violent maneuver. In AH I have asked two very good pilots to show me their version of this maneuver and one did exactly as described above but throttled back a bit to avoid going into a spin from the snap of the torque. The other pilot was able to do it full throttle with WEP and maintain control of his plane. I haven't been able to pull it off yet without throttling back, but at full throttle with WEP his reversal was an amazingly quick pivot.
The other version I have seen done two ways. Straight up at about 80 degrees, then a 180 degree roll inverted and then stick full back with flaps out and just enough throttle to get over the top but keep the loop as tight as they can as they pull their nose up. The other version they begin the roll during the climb but do basically the same thing at the top. I also see a little rudder and/or aileron as they go over the top to get their nose where they want it headed as they come down.
This is not a barrel roll as I was taught IRL, but I was not taught combat ACM or any consideration given to flying against an opponent, so maybe it is. I'm not on their six when I see this. It is their move as we pass the 3-9 line on a co-alt merge. It is also the move I see from good pilots if they come in with an Alt and E advantage and start to pick me to death...up and down over and over again with very quick pivots at the top. The first version is the move I do see often used at the top of a rope, but I no longer follow anyone up for a rope. If I'm at high speed sometimes I will go into a merge but not reverse and just look back to watch their reversal. If it's super snappy it gives me an idea of the caliber of pilot I'm about to go up against and I very often see some form of this. Of course I don't do this at slow speeds as they will immediately be on my six.
I'll try to find some film, but I was mostly watching all this 2 or 3 months ago and now it is buried in a million other films. But the next time I see one I will post the film.
I'm also going to go back to my trainer to see if he's still active and ask him to beat me to death in the vertical once a week so I can continue to work on this