If Pianoteq is fourth generation, is this a fifth generation piano?

Nope, more like generation 3.5 -- ironic, huh?  ;^)

Seriously, it's an improvement to the already-existing 3rd-generation piano instrument, not a truly "new" instrument by any means. 

I wish they would have cut the "extra sounds" from the video -- the demonstration certainly didn't need them!

Someone has built a piano that lets the player tweak the tuning easily by hand!