Weirdly, I remember in school when I was about 8, everyone in my class was given this making of documentary on VHS. Not sure why, I assume someone got a big box for free.

The way the article is worded, I would guess the material still exists somewhere, but has not been made available to the public.

Some enterprising individual should do some digging and see where that material is, and who has both access to it and the ability to release it.