|Nick Mason and Zappa.|
Watch the footage here
Zappa was the MC of the festival. For a long time it was debated if this jam really took place since Zappa denied it. Some years ago sound and photos began leaking out and on this film we can clearly see and hear Zappa sitting in with Pink Floyd.
The track is the instrumental Interstellar Overdrive. Maybe not the best jam, but still a historical document.