I'm not even gonna try that thing (it doesn't deserve to call a game).
But you can expect tomorrow a second video walkthrough of my hacked game, I've FINALLY beaten the 2 worlds!
My comments on the levels:
3-1 is pretty easy to do, but the only thing you should watch for is the small platforms, you can easily fall of.
3-2 is a bit harder, so be cautious there.
3-3 is very hard, I had to retry about 30 times to beat the level without save stating (with it is also difficult).
3-3 is almost impossible without save stating, I've managed ONCE to beat it without save stating, so don't expect to beat the level in a few hours, it may take a day or more...
4-1 is hard, but only because Lakitu's timing HAS to be perfect when you reach the way too big hole (I mean that you can't reach the other side, unless Lakitu 'helps' you
If you do the first part without mistakes, then about 340 (in game Time) at the hole Lakitu will appear (you must kill him in the beginning very quickly!).
4-2 is only hard after the warp (this one is just difficult), watch out for 2 Bowser fire and a Bullet Bill, when you reach the capitol P you must be small. Why? Because so far, I've NEVER managed to pass the obstacle as big Mario
but it's possible though...
4-3 is much easier, but only if you use the trap as an advantage (invisible blocks are normally bad, as a solid won't be a problem
Don't go too fast when Lakitu attacks you, because he can kill you while jumping (minimum chance that you kill him). Bullet Bill only appears if Lakitu is killed before the blockade.
4-4 is based on 8-4 from SMB2J, some modifications to make it a bit harder. Only advice for this is: Don't run all the time and use small Mario as your advantage in a certain area.
The video will guide you through those levels
It's here: http://www.youtube.com/watch?v=Ep21fIflUD0