What do you do on the last screen on Kingdom Hearts 2

Too bad you really cant do anything until you fully complete jimminy's journal...i believe it unlocks another ending trailer.

In American version, if youunlocked a secret trailer, it will play first and then the credit screen appears, then you must reset the game, so make sure you save before the final battle. Nothing else happens.
In the japanese Final Mix version, there is the option of saving on the credit screen, to get more unlockables when you load that new file.