To view your boarders master video get them to master level, go on their profile, go to the world circuit records and press A.

So far I've done it with Marty, Moby, JP and Kaori.

To activate these codes, you must enter them at the title screen. After you enter them, you will hear a sound effect.

To unlock Mix Master Mike: Hold L & R and press A A Z A A Z A A Z A A Z. Then select Mac.

To unlock alternate Elise suit (Mallora): Hold L & R and press A A Z X X Z B B Z Y Y Z. Then select Elise.

To max out stats for every character: Hold L & R and press B B Z B B Z A A Z A A Z.

To unlock all every course, rider, and board: Hold L & R and press A B Z X Y Z B Y Z X A Z.