My review
There are many sound libraries in the web. For example, findsounds is a great website wich has a search function to say, find "punch" sounds etc. Next time try adding sounds.
You must go to the flash protal and click on "get NG preloaders", then open the preloader and follow the instructions inside.
Now, as for your flash, the concept is too overused, there is this something on 13 year old kids that makes them think violence is cool and stuff. And that's ok, you can do whatever you feel like doing in flash, but try to make something with a story instead of mindless, pointless stick fights and related material.
You made a well use of the Flash 8 filters and, though the graphics were awfully simple, you managed to keep me interested enhough to view it 'till the end.
By the way, to stop a movie at the end to prevent it from replaying over and over, try clicking on the last keyframe of your flash. Once you clicked on it, press F9 and the actionscript panel shall open, put this into it:
stop();
This will make the movie stop at the end and it won't keep playing.