It always has to be something "inhuman" to explain overwhelming power, like with Itachi breaking out of the frog stomach jitsu. I love how it's a pattern that the villains always have something inhuman to explain their power (ie Gaara) but I guess it's fair for Naruto to have one as well but it's still pretty much a pattern.

My guess is Itachi sold his soul or something to a demon early on in life or stumbling on some otherwordly power making his own Sharingan techniques or something.

Overall a better epsiode though, those "cliffhanger" episodes can get irritating sometimes.