Audio of a 2-hour press conference with the cast and crew to promote Empire in 1980.
Star Wars - The Empire Strikes Back US Press Conference 1980 (Part 1 of 2)
https://www.youtube.com/watch?v=PS_8INT6Nx8
Star Wars - The Empire Strikes Back US Press Conference 1980 (Part 2 of 2)
https://www.youtube.com/watch?v=tCnPLisNJ5E
1980 documentary about John Williams scoring Empire: