To answer some of the questions in the thread,
I'm pretty sure Disney and expedia have an agreement under which expedia purchases options on rooms. If it can resell them, it exercises the option and then pays disney the remainder, minus its commission. If it cannot resell the room, it's out the money. Expedia purchases the options at a certain rate -- so expedia may have options on rooms at the fall rate even after disney has sold out of them.
An option doesn't really cost Disney anything during periods when the rooms are not going to sell out. So you can usually find any discount that disney offers for a particular period on expedia for such periods.
They offer the same rates, because if they didn't they would be competing against each other, and that would be unfair to one of them. If disney sold expedia an option on a room but then undersold them, expedia would be pretty mad. Converseley, disney doesn't want to be selling options to expedia and then have expedia underbid them.
Expedia's deposit and cancelation policy are, I believe, full payment at the time of booking. Full refund, minus $25, up to 5 days before check in. One night's charge after that and full charge once it gets to 3 days before check in.
As for disney matching a room price offered on expedia, that's fascinating they did that for you. I can't imagine expedia (and its lawyers!) would be too happy about that, although it's highly possible that I might be confused about some aspect of how the "options" work.