Amazing for a first run with flash! this is by far better than what I would usually see as someones first submission, you have obviously put some more time and work into it and for that reason alone it should stand to stay in eternal glory apon the grounds of new.
Couple of tips I could possibly give you are this:
Make sure you have a pre-loader, NG provides tons of them for free,
it plays on infinite loop, should have a replay button and stop once done playing through.
Even a few sound FX can brighten the entire thing and you can usually get them for free if you search long enough.
Art wize is not so much my field but I would say that some of it moves by a little too quickly for me to get a sense of what is going on, he opens a box and there is something inside it that makes him dissapointed? or the thing dissapears? its not realy quite clear.
All critique aside this is a very solid piece that shows you have artistic skills and can put them to use making something that is very watchable :)
- Cheers