Correct. Rybka believes it has the piece superiority and doesn't consider sacrificing a pawn to be an issue but the only pawn that it can sacrifice opens up tha

Correct. Rybka believes it has the piece superiority and doesn't consider sacrificing a pawn to be an issue but the only pawn that it can sacrifice opens up that side of the board for black. Nakamura explains a little before the sacrifice that if they exchanged queens it'd be almost certain that Rybka would have to sacrifice that pawn to avoid draw.