Hi Natalie,
A couple of comments:
"They are looking for stats who look like me." I would be interested to know what that could mean?
Also "It pays minimum wage" - you are not doing it for the money, and "they may even end up editing me out," nor for fame (unless you meant they are looking for stars and not stats who look like you).

Besides that, it sounds it could be really fun. From your other posts I gather you are new to Minneapolis and then it could be a great way to meet people you wouldn't otherwise meet. Academia is a very closed circle. You will have there three days of talking to people so at least unless it will be a really small group of stats, it's a nice opportunity.

As for it being a waste of time - obviously, but then you'll learn a lot of how films are made which is nice. From looking at films being filmed I can say it gets boring very fast, but then when you are in it, even as a stat who might get cut at the end, it could be fun? If you can think during the timeouts, that's not so bad.

And then, why not try it out and if you don't like it leave after 1 day. I doubt you'll be irreplaceable. But then again, maybe you did mean stars, or that they'll be very few stats.

One last idea. If you're there, you can tell them you are thinking of writing a book about them, and interview them at the same time, which will really be rubbing against glamor.