You know, I've heard my share of complaints from older folks about their inability to understand hip hop lyrics. Many say the words are too indistinguishable or that they move too fast for them to decipher what's been said. For me, this video beautifully illustrates a core aspect of rap performance that is much more important than lyrical comprehension. Rap lyrics are the textual conduit for the rapper's percussive and melodic aesthetic. In fact, I would argue that what an emcee says in a verse is rarely as important as how s/he musically shapes the verse into something pleasing and exciting for the listener.
"It's not enough to know which notes to play, you have to understand why they need to be played." George Carlin commenting on the blues
This brilliant kid has already made this discovery (as kids will do if we simply leave them to their explorations). As soon as he reaches the age of adding lyrical content to his already sophisticated sense of musical awareness (and if he keeps rapping), he's going to be an absolutely magnificent emcee.