That instrument you mentioned is a Champan Stick
:P In fact Myung plays 'New Millennium' with a Chapman Stick, check Live at Budokan
And that guy you saw playing it, you don't recognize him? you're a DT fan man, the master Tony Levin of Liquid Tension Experiment.
I love the setlist, except of The Dark Eternal Night, I think it doesn't suck, but it's not DT, too forced by the evilness and middle-age crysis of Portnoy. And besides I already heard it in 2008, so I don't want to repeat that tune again, but I'm assuming I'll be anyway hahaha.