Whether this is actually Sephiroth speaking through the JENOVA-S-cell connection with Cloud or Cloud just imagining he is hearing Sephiroth while Sephiroth is still asleep I am glad they actually mae Sephiroth say "Cloud". When he was in the state of awakening while running around with Jenova in the original he had no idea who Cloud was and that does not fit the grudge he is holding over getting beaten by random blue guard who went all loser turns hero. It makes it more believable they are actually nemesi.