Tarrasch - Capablanca, 1914


After the first correct move by white, there is an explanation of what white actually did in the game, and why it was bad.

This explanation contains an error, and I don't understand the explanation.


The error is: "18 ... Nxg5" is mentioned in the explanation, but there is no peice to capture on g5.


The explanation from the lesson is included in the diagram below. Assuming they mean 'Ng5' instead of 'Nxg5', is the rook capture for white not worth having the king so out and vulnerable? (Is there a mate threat looming?)