The Super Mario Maker book (also available on Nintendo's website) has a number of pictures in it with a key icon followed by a 4-digit number.
I assume these are used in-game somewhere... but what are these numbers used for?
1 Answer
If you open the in-game manual, the Main Page of the manual has an icon with a key and four empty squares.
If you choose this icon and enter one of the video IDs, it will show a "hidden" video.
