Tusk video?

[elie]

Hello everyone!
I just registered a couple of days ago and today my account was validated so I thought I should ask a question. I hope it's ok that I started a new thread.I have to add that I am a relatively new FM fan- I mean I had a couple of albums when I was a teenager but I sort of rediscovered them lately and I am really into them now.
I was looking for some videos on the internet the other day and I came across something called "Tusk 1979" or something like that. I downloaded it and it turned out that it was some kind of a recording session - FM with the USC band at an open stadium or something. It looked like a documentary footage, you could also hear the members of the band talking and at the end (it was not very long, 4 minutes maybe) there was Stevie Nicks dancing with a twirl baton (is that the right word?? english is not my mother tongue ).
Does anyone know what this is? Is it perhaps a part of a longer documentary/making of kind of thing?