Nice programming, needs some tweaking
The ActionScript piano is a nice programming accomplishment. The layout is good, but there are some adjustments which would make this more intuitive.
1. The arrangement of the first set of Blue Hot Keys makes sense, with the letters A,W,S,D,R,F,T, and G corresponding to chromatic notes on the scale. But the second set, H,Y,J,U,K,I, and L gets confusing on the keyboard, since the note F# should be placed physically after the F-note, (as the U key on the keyboard), but instead is placed physically behind the F-note, with the Y-key. The same is true for the G# and A#, they should be relocated one step to the left on the computer keyboard.
2. For some reason the beats do not loop for more than a few seconds, and then they stop.
3. The Big Blue Button displays instructions for playing some songs, but as soon as I hit a note, the instructions disappear.
Otherwise, this is an ambitious project, and I'm sure your next version will be great!