Dynamic Soaring
Here are two video clips (15Mb and 21Mb, I'm afraid) of my brother David Woods Dynamic Soaring at Ivinghoe Beacon, Bucks - he was demonstrating to me how to do it. The wind is on the north face about 10mph and the DS'ing takes place on the south facing side on the ridge.
The video is from a still camera (Canon G5) using its movie facility at 15 frames per second, hence the poor quality. Cursory analysis reveals the model (an Elita) is probably hitting 120mph at times.
106_0678.AVI 21.2Mb
106_0679.AVI 15.5Mb