Decent tutorial.
Not bad. I like tutorials that include Frame-By-Frame. However you might want to take a cue from one of you own lessons here. Your music select buttons should turn off any previous music in favor of the music selected. As it stands you can press 1, 2, 3, and 4 and have all the music tracks playing at once. Script them so when pressed the button turns off all existing music then plays the selected track. You shouldn't have to push "Music Off" every time you want to listen to a new mmusic track.
Good work, keep it up.