I'd go for high ISO, evaluative metering (after all, you can't choose what your are metering off of), and I'd tell it to underexpose by 2/3 stops. I'd also use a relatively narrow aperture to help compensate for focus differences. Something like ISO 1000, AV at f/5.6, AF, and -2/3 exposure compensation.
Here's why. The high ISO means that the camera doesn't need much light to take a picture. Overall, the show isn't that bright (compared with people standing outside). It also involves motion, so you need a relatively high shutter speed to stop that.
The performers are relatively brightly lit but the background is very dark. If you use evaluative metering, it'll overexpose becaues so much of what you are shooting is dark background and the camera will try to let in enough light to make the background look brighter. To compensate, you tell your camera to underexpose or let in less light than it thinks is necessary.
Normally, you would get around this problem by switching to a metering mode that didn't pay so much attention to the background, but those modes assume that you'll be aiming at your subject. If you are shooting from your lap without looking at your camera, your aim is bound to be bad, so you can't rely on center-weighted, partial spot, or spot metering.
The F/5.6 aperture on a moderately wide angle lens (can't zoom in too tight when you can't aim) lets there be a pretty good range of the picture in focus. This way if your focus is off by a little, you are still OK. You could use a higher f-stop to allow more of the photo to be in focus, but at some point you start to run into problems with the shutter speed being too long.
Another approach would be to set your ISO as high as is acceptable with your camera, set the shutter speed to something that will do a reasonable job of stopping motion (1/125?) and take your chances on the aperture. Maybe it would be best to look at the EXIF of the pictures posted here to get a better idea of where the exposure sweet spot is for this show.
Of course, I'm not recommending that anyone photograph something that they've been told not to. That would be wrong. I just thought it would be interesting to think about how to do it.
I bet you're a riot in Disney. You wouldn't believe the butt chewing I got from a CM because I took a picture of an empty sea shell cart getting off the Nemo ride in Epcot. For a minute I thought she was going to send me to time-out.
if he could have gotten that close to Nemo!! I wonder if it is a character "meet n' greet" type contraption. You saw this backstage where the Nemo musical is or where the parade comes out??
