Essentially, the AAA "enhanced" or "multi" FP disconnects all the machines so that you can collect a FP from each attraction offering FPs at any given time. For example, at 10 AM you can collect a FP for Indiana Jones that may have a return time of 11:30-12:30. Normally, you would not be able to collect another FP for any other "linked" attraction until 11:30. With the AAA enhanced FP, you can still collect a FP for Buzz, Splash Mountain, BTMRR, and any other attraction that is offering a FP without regard to the Indiana Jones return time. You will, however, not be able to collect another Indiana Jones FP until 11:30. Obviously, you cannot collect FPs for attractions that are not offering FPs, including those that have run out of FPs for the day.
Hope that's clear. I had the AAA FP once before and loved it. I will also have one for my upcoming August trip. I think it's going to be such a wonderful benefit during the busy summer season.