This event is held in an outdoor theater, across from the American pavillion in WS. You enter, get seated. Then at the start, choruses from the area, march in, in robes holding candles. They are singing. They march up onto the stage, where they go to either side of the stage, with a full orchestra in front. Then, Disney CMs enter, and for a human Christmas tree. There will be a celebrity narrator. The narrator reads parts of the Christmas story, with a particular Christmas/holiday song sung by the massed choirs. Then, another reading, more singing. It goes on this way for about 40 mins. It is really quite beautiful. My Christmas isn't complete without at least one performance.
Now...will a 10 y/o enjoy it? Hard to say. My 10 y/o dd loved it, but she attends church, and loves music...so not much new or different there.
Basically it's the telling of the Christmas story with musical interludes. Very moving, very beautiful.