What he's referring to is a leak of around 1000 development versions of various games for Sega consoles. Of course the thing I'm wondering is why they were in a form that was able to be leaked like that. They're not meant for playing, more for ripping apart with a Palette/Sprite viewer and seeing what you can dig up about the game's development.
An example: Ristar was one of the games that was leaked. The string "CAUTION -
RISTAR- IS NOT V O L T !" is found in ROMs going back to the earliest found, which would imply an internal struggle over the naming. It's interesting to see what changes are in each ROM version. It's more for sh*ts and giggles than anything else.
EDIT: @Dalek: Surely you should have used the cross-eyed one