"Daxflame" plays a spastic grade-schooler named Bernice Juach, who tells stories about his life (such as when he bought a car on eBay with his mom's credit car and failed to convince her he thought it was a Hot Wheel). My source at YouTube says he's an actor, though the only press he's gotten stresses that no one knows if he's real. And that's why the kid (who's also appeared with the mediocre but dominant YouTube comedy group Smosh) is so good.
"The Funniest Fake YouTube User." Gawker. 15 Jan. 2008 <http://gawker.com/>.