Bounceback can mean a discount on the room rate or an offer for
free dining. There are certain rules that apply.
You must book your return stay while you are at WDW. You should receive a brochure that tells you the available return dates. If you don't, ask about it at the front desk.
For the room discount bounceback, If rooms are available, you can book a room and receive 30 percent off the regular rate for these dates. (Deluxe Villa's can be 40% off.) Moderates may be 30 percent or less (I'm not sure) and obviously this depends on what WDW offers at the time you are there.
As I said, you must book before you checkout. The in room resort phones have a reservation phone number on them. Plan on spending a while on the phone. (I spent 45 minutes.) The rate they quote you will be the discounted rate (assuming you qualify etc.). You simply need to make the standard deposit for a room only reservation (but note there is some dispute about whether the cancellation period is now 6 days or 46 days before the stay).
Not everyone gets a flyer (I didn't). Some people learn about bounceback offers through flyers in the room, on the tv channel or by asking. For those at the Contemporary, it will be on the in-room computer.
You do not have to rebook for the same time the following year - just rebook for a return stay within one of the available dates. If you are going in November, they may not yet offer a return date for November 09. (When I was at WDW in December 07, the bounceback offer only ran through August dates.)
My recommendation is to rebook for an available date in 2009, then monitor the boards to see when(if) a bounceback is offered for November. Then call WDW and asked to change your bounceback date to the November date. I do know you can change your dates upon returning home. I don't know extending it in the way I describe will work, however, but as long as you call at least 45 days before your return stay, you can always cancel if they won't let you change your date.