Wow... That's actually very impressive. It's tough to catch the ball in the position where you can transition to a between the legs after throwing the ball off the ground for a self lob. It's easier off the backboard because it's easier to anticipate where the ball is going to end up.
That dunk's a lot more impressive than the one-hander that made the rounds a few days ago. I'm wondering though, what's with the renaissance of LeBron James pre-game dunk clips? He's been doing these dunks in pre-games for years, yet it feels like people are surprised to be seeing him pull this stuff off. From 2009-20010: http://www.youtube.com/watch?v=Faw0_MvV-6k