I just been wanting to ask this question.
Out of my 3 visits to Disneyland. I notice this event goes on with Band Leader Mickey in it, in front of the castle. So, far I have only caught it on Sundays while getting ready to attend the MiceChat Meets . They start playing Walt Disney's Welcome speech and then Bandleader Mickey starts marching around Main Street and along with a band.
I just wanted to know. Is there a special reason why they do that? Is it just Sundays? That's the only day of the week that I have caught it.
Here's some pictures of it.