It sounds like it's had post production done to it.
For example, he sings the "Pokemon" and then goes into "Gotta catch em all" while the word Pokemon is still being sung out. It's seriously not possible for him to do that.
I'm not saying these aren't updated vocals necessarily but they have been mixed and over-dubbed, with other layers of dubbing over it. And the mix is so close to the original mix it's a bit of a strange thing to do really.
Still pretty cool.
Edit: For giggles I've compared the waveforms of the original full album version and this new recording and they're identical. He's just lipsyncing it seems I am afraid.
It's literally a perfectly identical waveform between this and the original album release back in the early 2000's. Even if the backing track was the same, the vocals wouldn't be. Literally a trillion to one chance of making a brand new mix and getting it perfectly identical to the old one.
