Although is is true that the four making of documentaries were released in the 1990's in japan on laserdisc remastered And laserdisc is an analog format i do believe they made new digital tape masters. And they of course had digital audio.

Really does not matter if they were on d1 or d2 format however as they would never even be beyond SD quality.

Sure Lucasfilm could have tracked down 16mm prints or even tried to find the negatives and scan in HD but using existing digital tape masters was much more useful in terms of cost. Why they did not include the fourth making of film is hard to make heads or tails of.

I don't believe the conspiracy angle either. About it showing Lucas being too candid about story over effects or that he changed his mind about things when making the prequels or when it comes to the story of darth vader.

I believe the making of masters of the blu rays is the same master as the last one used in japan minus the subtitles. Unless Lucasfilm went to an earlier non remasters not digital source like the US vhs tape master and digitized it which would cost more money and make zero sense.