The history of Heavy Metal Parking Lot linked below is a really entertaining read.
“What strikes me about the film is that it’s really nothing about [Judas Priest] at all,” she says. “This is a movie about the fans. It’s their story. It takes place in a parking lot, not a concert stage, and it does feel like you’re getting this in real time. The daylight never changes. And when it ends you’re not sure what you should think about it, and that’s where the art is in it. And it’s a great example of somebody going out and doing their thing and then distributing it, like DIY with punks. The fact that it made no money adds to its charm.”