THe one you are thinking of is Backstage Magic, it takes you behind the scenes at Epcot, MGM, and the MK, but not the AK. I've taken it twice, it was great! Well worth the $$. I also loved the backstage tour at the AK.
Did you know that many of the deluxe resorts offer free tours taht run 30 minutes to an hour usually one day a week? If you are staying at a deluxe, be sure to enquire.
Anne