World 3-2
It's the only level in that video, but I was feeling likely to screw up 3-3 so I decided to make a break there.

World 3-3 and 4-1
3-3 does have a few tricky spots, but 4-1 has almost nothing to it. I guess they figured the ice would throw you off so everything else was toned down a lot.

I think it's something like 21 minutes total between all the videos so far and already almost halfway through World 4.