He gives two bullet points for why he doesn't vote:
1) It's meaningless! Your vote is too small to affect change, and besides, the choices are garbage anyway.
2) If you don't vote, you aren't a part of the political system, and therefore don't have to take responsibility for the result.
I find this line of thinking despicable. It doesn't take a lot of research to learn that the franchise has been one of the most embattled "rights" of the American citizenry, because it's not a right at all. The 15th amendment, the 19th amendment, and the 1964 voting rights act were all steps towards turning the "right" to vote into something general instead of specific to rich white men. They were steps towards democracy. They were all, in their own ways, social revolutions.
The idea that the voting is meaningless is to neglect this history, and to disregard the entire concept of political activism. It's quite a privileged thing to say. George Carlin was a straight white male, and in the above video sounds like he's never considered that voting might be a way for people to defend their rights or assert their own political prerogatives.
It's easy to poke fun at the American electorate, and to harbor a deep cynicism for voting altogether. But it's not very thoughtful, or productive.