I got this info for you from allears.net:
What is the Fantasmic! Dining Experience?
The Fantasmic! Dining Experience includes dinner at one of the participating Disney's Hollywood Studios restaurants and reserved seating in the Fantasmic! amphitheater. As of this writing, only Brown Derby, Mama Melrose, and Hollywood & Vine are participating.
This means that instead of waiting in line for 60-90 minutes outside the theater, you can walk right up to the theater 30-45 minutes before show time, (no waiting in a long line!) and still have a seat.
Is there a charge for the package?
There is no additional charge for the package itself. However, the package, which includes the Fantasmic! seating pass, MUST be guaranteed at the time of booking with a credit card, and a $10 cancellation fee applies if not cancelled at least 48 hours beforehand.
As of June 2009, you may order from the Brown Derby a la carte menu.
Mama Melrose $32.99 adult/$11.99 child (3-9) not including admission, tax, and gratuity -- Dinner package is price fixe: appetizer, dinner, dessert and non-alcoholic beverage.
Hollywood & Vine $26.99 adult/$13.99 child (3-9) not including admission, tax, and gratuity (no characters). All you care to eat buffet. Choose from a number of selections including; oven-roasted Prime Rib, Citrus Baked Chicken, Pan-seared Salmon, and Stir-Fry Noodles with Sesame. Also includes fresh salads and build your own ice cream/dessert bar. Adult beverages NOT included. Child's meal includes beverage.
All packages include a special pass for seating at that night's Fantasmic! and dinner at the restaurant chosen.
Report to your restaurant 10 minutes before your Fantasmic! Dining Experience Reservation, and you'll receive your special Fantasmic! seating pass at that time. Theme park admission is NOT included.
Can I Use the Magic Your Way Dining Plan with the Fantasmic Dining Experience?
Yes, the Magic Your Way Dining Plan can be used to purchase a Fantasmic Dining Experience. You can also get the Fantasmic Dining Experience if you have the Magic Your Way Premium Package or the Platinum Package.
Hollywood & Vine and Mama Melrose's Ristorante Italiano both count as one Table Service meal for the Dining Plan, while the Brown Derby counts as a Signature experience, or two Table Service meals.
When you call to make a reservation, your credit card number will be taken, but the charge won't be put through (unless you are a no-show, or do not cancel at least 48 hours before your dining date). You will pay with your Magic Your Way Dining Plan when you dine, just as you would for any meal.