I exchanged a few emails with "Tommy" back in 1998 and if I remember correctly he said that he tried the loops with different entry airspeeds. That may be why one of the ones in the video ends up with a high recovery but the other one and the one in the still photos seems to have a pretty low recovery altitude. I don't remember any more detail than that. He also said the CAA yanked his license for it but he got it back fairly quick though.