Since the video was made in 2009, it probably is the K2600. There is also a video using the same keyboard to demo a sampled Kawai EX concert grand, and played by professional pianist, Jonathan Story. What I was interested in was a keyboard that can easily handle the performance demands put on it by these two players.
However, Kurzweil's website says the K2600 is a discontinued model. As far as I can tell, its successor is the PC3K8, and there are demos of that online as well. The built-in grand piano on this sounds very good, too, but Lance Herring's sampled Steinway & Kawai sound terrific!