I saw a superb glider display at Duxford last year, part of the display he was being towed whilst doing aeros?! Then he finished off the display on his own.
I was so amazed by the whole thing the only photo I got of it was this one, and no - I didn't turn the image upside down..
Thanks for the initial vid, I am now sitting here at work staring at the sky outside and largely achieveing nothing...