That may be true, but Euphoria runs alongside the existing game engine.
I personally don't think they are using it, BUT they are definately using a more complex and revised version of the 2K5 engine. There's just so many things going on that gives the game a very human look to it.
Euphoria isn't the cure-all. I've watched that video a bunch of times now. From fast to slow, backwards, sideways and standing on my head. It's all about 40 seconds into the video and #81's block that trips up another player running by. Whether or not it's Euphoria is becoming a non-essential.