Bet they had to work to keep it below Vt.
Nice flight.. I've seen another video on youtube along a coast line. I think it was a Pawnee towing, or a Pitts biplane, and the glider doing acro.
Have to go find that one.
That looks tricky... I'll never complain about our tow pilots again.
Question: does the rope have a swivel fitting or something, or is the twisting just not a problem?