I swiped this off All-ears:
"The first three hours of parking are free. You can obtain an additional two free hours by getting your parking ticket validated at Downtown Disney's AMC Theatres or any of the table service restaurants. After the three free hours (five hours with validation) the cost is $6.00 for each additional hour."
Sounds like a great way to kill a few hours. Don't know about how full it would be on Thanksgiving.
PHXscuba