I have a VHS copy of this show... got it from a long time trader several years ago, along with the Sesame Street out-takes.
It's a really interesting program...not really a formal interview... if I remember correctly, they're laying in the grass, just talking. Some of the discussion is quite interesting... talk about the future of film making, independent filmmakers, etc.
I believe they show some of his other college films (or clips), not just THX1138.
It's funny to see a really skinny Lucas...
I'll have to see if I can find it.