Some talk on the supercub forum is that it was 20 on the nose. Perhaps it was... It appeared that you could have run beside the guys doing the steep approaches and kept up. It was a stiff breeze at any rate.
Regardless of the wind, it seems apparent that the constant descending slow-flight to the spot/line is a better way to do it for reducing forward speed. So many of the competitors, at least in past contests, drag it in low and slow and then plunk it down. He was using the rudder a bunch to keep his wings level. He also has an airfoil tail and some fairly giving suspension.