All these white boxes are a custom MIDI system made by YES Audio under the orders of Vangelis and especially for his playing needs. The big terminal white boxes write on the back side "YES AUDIO, CUSTOM DESIGN FOR VANGELIS". This custom setup is connected to various synths, mainly racks. Also he uses 17 foot pedals, 16 volume and one sustain pedal as you see in the video. All this system help him to play live without the need of overdubs and sequencers. In fact, Vangelis compose/arrange/play and record at the same time! Its a unique technique and he is using it at least the last 25 years, this MIDI system is already in use since early/middle 90s.
Comments
za https://www.reddit.com/r/WeAreTheMusicMakers/comments/3ixi30/this_is_the_most_insane_and_incredible_midi/
http://forum.vangelis.fr/viewtopic.php?t=1304