Highly detailed look at the making of 20,000 Leagues.
Watching this adds to the entertainment value of the movie itself. Once you know all the nuts and bolts about the production you respect the movie itself even more. Being a fan of Voyage to the Bottom of the Sea (movie & TV series) I found it interesting that the submarine Nautilus and submarine Seaview both used the same studio tank for miniatures (at 20th Century Fox studios).
As explained here, there were two filmed versions of the giant squid attack. The unused "sunset" version and the version we got in the final cut. The deleted version is more clear and pleasing to the eye.
It is not often we get a 90 minute documentary about a 50s science fiction movie...they are normally much shorter. Great stuff.