[hinoki]

GameCube used a mini DVD, but broke with the standard by using constant angular velocity instead of constant linear velocity. So the drive always spun at the same rpm, where regular DVDs spin slower the closer they read head is to the centre. This made them cheaper to make, and impossible to copy with a regular DVD burner.

[aahacks]

GameCube can play backups from a burner. It requires either a modchip or Swiss with Action Replay. Also a laser adjustment may also be needed.

https://www.youtube.com/watch?v=kUQ1GFPG9q0