if you want the visualizer to work, click yes on the microphone thing and use speakers. also, it might not work well if there's a lot of background noise or your volume is too high/low after one or two plays the visualizer might start to glitch :( if this happens just use the flag button to start the project.
the song is echo, written by crusher-P and sung by gumi: https://www.youtube.com/watch?v=cQKGUgOfD8U art is mine, character is crusher-P's visualizer script from coockiecrafter: http://scratch.mit.edu/projects/27568204/ (i edited it a bit)