To answer your question, that is Roscoe Johnson of the Harlem Wizards, a 6'3" guy with hops who has dunks all over the YouTube. But you’d be hard pressed to find a better one than this.
I’ll say this again — if you want to liven up the All-Star Weekend dunk contest, let a few of the pro dunk guys in the mix. I don’t care if they didn’t play in the NBA, this is a dunking exhibition.