Vangelis was interviewed in his studio NEMO in 1984 in a piece titled "Vangelis - The Man and His Music", there are a few dodgy VHS copies floating around on Youtube, but now Youtube user Nimanty has re-edited and remastered to give better quality, and now stereo sound.
Go on, treat yourself..
Older Music Machines & the People Who Still Use Them
Part 2 on revisions that made synths into brand new machines
Revisions that turned synths into brand new machines