Unlock Supreme Sweeper:
Get all 80 cat medals to unlock a scene of Kitty the shopkeeper with the Supreme Sweeper. It will now be available at the final shop for $90,000.

Extra FMV:
Beat levels 1-1 through 8-4 with a "A+" or greater rank. A new FMV of the developers will be unlocked in the "Collection" option.

Thanks to Revolution readers darksider and yannic!