Good game
This is actually quite well done, I would have to say. However, as much as I'd hate to, I gotta nit-pick; since it is a beta according to the maker's words, then hopefully this would help him know what to look for when he goes debugging and stuff ;-)
a)do try to fix the collision detection; there were a few spots where it would have him still walking on a platform that wasn't visibly there.
b)If possible, try to see if there's a way to cut down that file size - it is quite good and well-featured, but you have to think of those that are on slower connections :(.
c) how about some enemies? ;)