I just returned last week from Ft. Wilderness and the Camp Fire Sing Along was great!
They have a small outdoor area with fire pits on either side - you roast your marshmallows & make smores there. Inbetween is adequate seating for the sing along. You're welcome to roast the marshmallows when the fire is started, during the sing along and even during the movie.
They have a very nice lady who plays the guitar and sings basic camp fire songs. She gets the kids involved and they really love it. While she's singing, Chip & Dale come and greet EVERY disney guest. They ask that you remain in your seat for that and they'll come around to you.
After the sing along, they start the movie! The little conastoga wagon that sells the marshmallows remains open til 10pm and sells popcorn, sodas & snacks. A great time......I highly recommend you attend it at least once.
Enjoy!