It really depends on what you want to do, just learn to play, learn about synthesis or both.
The synths in the video are I think, (Left keyboard stand)Roland D50 digital synth discontinued, Novation Supernova or Supernova 2, again discontinued, (Right Keyboard stand) Supernova again I think and Roland X6 Workstation again discontinued.
The differences are the D50 is monotimbral, meaning one sound at a time and a maximum of 16 note polyphonic
The Supernovas are 8 part multitimbral which means up to 8 different sounds at once and depending which version from 20 to 48 note polyphonic. These are great for tweaking sounds in real time.
The Roland X6 is a workstation meaning it can be used to compose complete songs, so it has a built in sequencer, max 128 note poly, 16 part multitimbral, ths model is also capable of sampling.
Feel free to pm me if you need any more info/help