I don't find it difficult to do....but doing it PERFECTLY every single lap of the race with guys as fast (or faster) breathing down your neck is more difficult.
Notice in the vid, they actually have to move their elbows up from touching! They are able to hit nearly 70 degrees of lean angle, all on a tire patch of less than 10mm!! Also note the counter steering happening. You can clearly see he's going around a LH corner, but the front tire is turned right. Good stuff!