Pop: I have also looked for a video but without success, and you are right about him working it out beforehand.
This is from the book about him, written by Bill Zuk with Janusz Zurakowski.
Zurakowski would often resort to mathematical calculations to explain his theories, but when he tried to Show Jim Heyworth, chief test pilot for Rolls Royce, that he had come up with something different, Heyworth was baffled.
Zura said that he had discovered a new aerobatic manoeuvre and demonstrated the theory of it on paper.
As the complex formulae were laid out in a series of notes in Zura's Hucclecote office, the RR pilot couldn't grasp the idea of a tumblinmg flight path.
Knowing that Zura was a very competent engineer, Heyworth believed there could possibly be something there.
He had little idea that he was being shown the beginnings of the Zurabatic Cartwheel.