The types of things I think a "backstage" tour could provide are limitless. During the Fringe Festival just last week I walked by a theatre and heard the company going through what I would guess was a warm-up ritual. What I might want to know is, what are they doing? Why are they doing it? How can/does the ritual make the performance better? I would love to see that ritual.
Ok, I must be honest. I am not a fan of Cirque du Soleil. They do have a great video, however.