At around 2:06 of the demo when he is playing with one hand I was wondering if he was using the Chord sequencer feature?.
I have yet to try it on my Pa3x...but it looks and sounds like a interesting playing concept.

Especially if you set up a Korg EC5 to trigger it into record and play (doing it from the front panel requires a precise 2 button press), I think you are going to be astounded at what you can do with the CS, Donny. Particularly with you as a singer, you are likely to be doing an intro, then 1st verse, 2nd verse, bridge, solo verse and out type structure on a lot of songs, simply press CS record at the start of the 2nd verse, and CS stop (it's the same button/switch) at the end of it. Now do the bridge, get ready to hit the CS Play switch, and at the end of the bridge, off you go!.

You can now play anything you want, any way you want it, and the verse chords will loop for you. Take one solo... take two! Use your LH for the bender on sax solos and rock guitars. Play your accordion! Walk out with a radio mike and sing direct to the tables... whatever you feel like doing. And do it differently tomorrow, because it is STILL arranger play, not some preset karaoke gimmick.

Trust me Donny - it's a 3rd Hand...!

I'll be digging in to the CS very soon on my Pa3x, I see where it can be very useful.....thanks for the tips... wonder if Yamaha will ever incorporate the CS in their arrangers someday also?..