Wii Backup Disc
The Wii Backup Disc is a service disc apparently used inside Official Nintendo Repair shops to transfer personal data like savegames and console settings between Wiis as part of a repair.
It's not entirely clear what it does; something it does *not* do -- even though it appears it might -- is allow VC games to be transferred between consoles. Instead, it transfers the license so that the user can redownload the games from Wii Shop Channel for free.
Note: "Change WiiId" is mostly useless. WiiId is only used as your "Wii Number" that you give to your friends so they can send you Wii Mail. When you pick it, it assigns you a new random ID.
It also doesn't boot on full bricked Wiis and it's unlikely that it repairs half bricked Wiis since delete all only deletes savegames/settings and not any channel content (Weather/News/Games..) or the firmware.
The so called "DevCerts" are two .wads on the disc FS called 'dummy-cls.wad' and 'dummy-loc.wad' both have one content which is 0x40 bytes one is empty the other one seems to be just random data. The 'dummy-loc.wad' file also has a CertChain which only works an a devkit. 'dummy-cls.wad' has a ticket which the Wii doesn't accept, therefore you can't install it.
(insert more explanation here)