The Beatles' two surviving members boosted the launch of Scorsese's doc, screened at London's BFI Southbank. McCartney described George Harrision as "a great man" and told the gathered media that the film had made the memories come flooding back.
"Every time I see something to do with George it brings back more memories than you would believe," McCartney told the press. "He was my little mate on the school bus. A lot of fond memories. He's sorely missed by us all."
The documentary is set to receive a limited cinematic release before being shown on HBO in the U.S. and on BBC in the United Kingdom.
"Material World" is split into two parts -- first chronicling the Beatles' rise to fame, then documenting the solo years, when Harrison juggled music with philanthropic work and a career as a movie impresario.
Five years in the making, the three-and-a-half hour film was pieced together as Scorsese worked on "Shutter Island" and forthcoming 3D family film "Hugo." Harrison's widow Olivia, who also has a producer credit, allowed Scorsese access to the family archive of photos, home videos and personal effects.
Also on hand in London were the Beatles' former producer George Martin, Yoko Ono, Oasis' Noel Gallagher, and Ronnie Wood of The Rolling Stones and The Jeff Beck Group.
Often called "The Quiet Beatle," Harrison died in 2001 from lung cancer.
(Additional editing by Jillian Mapes, Billboard.)