Here is a demo of how it works:
http://www.varranger.com/vforum/index.php?action=dlattach;topic=1878.0;attach=1158

The very nice Novation SL61 MKII work the same way.

Lee

my old Roland g1000 could do this?...what is the difference with this then using a smf with markers to control parts?

Dnj, what you hear is not a smf but a style.
You don't see it, but he is playing the chords with his left hand

he is using a Novation Launchkey 61 midi master keyboard, and is selecting the variation A B C D , fill in, Ending.. with a physical button

The new thing here is to get the master keyboards buttons to light according to what you are doing

But you are right the same buttons can also go to smf markers