Go for it! I am very into the idea of this being preserved on DVD. I spent quite a bit of time on a BMX freestyle bike myself back in the mid-80s (when I couldn't get hold of a skateboard), so this one is definitely close to my heart. Along with BMX Bandits, it was about the only BMX movie out there then, and was big news for me at the time. I found BMX Bandits on DVD at a truck stop for 3 bucks a while back--score!
Speaking of Gleaming The Cube, don't forget Thrashin! as well! Both are available on DVD, though, but Rad! still is not.
Sounds like a project.
--SKot