Star Wars: The Making of the Myth - hosted by Anthony Daniels
https://www.youtube.com/watch?v=kv_4AV35I2s - from the marcus shepherd YouTube channel (40 mins long).

The blurb:
“Star Wars Documentary made to celebrate the 1977 movie and explore it’s creation, roots and sources. Presented by Anthony Daniels (C-3PO) Directed and Produced by Marcus ShepherdD. It was devised, written and filmed using rare archive - much unseen since the actual 1976 shoot - and featuring interviews Mark Hamill, Kenny Baker, Steven Spielberg, Brian Muir, John Jay and others with a unique take and involvement in the movie.”

I couldn’t find an IMDB page for this documentary, and (as darth-gary pointed out to me) despite some claiming its from 1997, and the doc featuring pre-SE ANH footage, the end credits clearly states that it’s from 1999 and was made by Sky Movies. It’s possible, and this is only speculation, that it was made for ANH’s 20th anniversary and then aired again in 1999 for the release of TPM, hence the unaltered movie footage. If you know anything else about this doc (especially when it was made) please let me know so that I can update this post.