BUMP,
I too dont understand what this is and how it works? Are you really waiting in line for two hours?
We just did this last week, and yes, someone from your party has to stay in line.
We did it on an EMH day, got in line about 8:30 and there were already about 15 families in front of us - although it was hard to tell, because many families left one person in line while the rest of the group went off to do rides. The CM do tell you that this is ok, as long as the kids are back in line in time to sign up.
The first show was at 9:50, at 9:30 the CM counted out the first 15 kids, asked them a few questions and put them on the list. We did not make the first show, but were first for the second show. After the first group is selected, the CM lets you know what time they will be signing up kids for the next show. We just all stayed in line so the kids could watch the first show. I grabbed breakfast from Starring Rolls, and brought paper/pen for the kids, so they were pretty content just waiting. While I waited in line, DH grabbed TSM fastpasses.
If you are not staying at a Disney resort, you may not want to try to do this on an EMH day, you definitely won't be in the first 2 shows.
I also recommend looking this up on
youtube first. Many people didn't know what it was, they just saw a line and got in it. At least 2 families right in front of my group backed out after their kids actually watched the first show because the kids were too scared! What a waste of over an hour!
My girls loved it, and I would definitely recommend trying it if you can get there early!