There's a couple of different things that could be. If he was nose up and stalled it before using torque to whip then nose down and around really quickly, that could look like a snaproll if you're also overshooting as it happens. That overshoot in a rolling scissors looks kind of strange for some reason, almost like the guys plane is just revolving in mid air. If that happens during that trademark 109 vert reversal, that could account for the crazy way that looked to you.
Basically you hold it straight vert with full rudder and stick as necessary. When you get it to the speed you want, chop throttle, push the nose forward, kick left rudder as needed and jam the wep on. The nose will whip down and over. Then you can control the direction you come out of the maneuver with your throttle so that you pull out wherever you like.
That thread they mentioned is really good to explain it, Agent has some drills to practice to get a handle on it, and there are a few films in there as well.
In the right situation, it's a fantastic move and I love it.
