Pretty Good
The only thing that bothered me was baby mario crying at the beginning. I have DSL so it's not that bad but it might get on the 56k user's nerves. Another thing that would greatly enhance this movie is sound effects.
I really suggest adding some SFX. I know it takes more time, but it'll pay off, believe me. When Kefka laughed, there was no laughing sound! I was disappointed in that. But other than those things, this was an awesome movie and I hope you win the contest.
-Vince