An X-cross, I believe, is an extended cross, which is essentially a cross with one F2L corner-edge pairing already completed and inserted into the correct slot.
An X-cross, I believe, is an extended cross, which is essentially a cross with one F2L corner-edge pairing already completed and inserted into the correct slot.
^I've only watched the first 2 minutes of that video, but that's not really an extended cross. With an x-cross you're doing both things at the same time.