Boooo.
Nice test for learning Actionscript. It works, at least, as long as I played it (not long.)
This is possibly the worst, most innacurate port of Tetris ever. There are plenty for Flash. Yours is in the lower ranks. You didn't even color the pieces right. I don't think the height/width was correct, the tiles moved slow as fuck. It didn't display where they'd land at the bottom (which rocks), and it didn't move smoothly. Not to mention you had to bash down to get it to go anywhere.
WAY TOO SLOW! Horrible, annoying, high pitched music made it even worse.
Keep up the Actionscript work, just... try to play your game a bit before you post it. Just cause you wrote some mad code doesn't mean it's fun.