This is pretty interesting and I find it funny just because he was treated as kind of douche bag in the documentary King of Kong. Turns out he submitted a score to Twin Galaxies that was made with the emulator MAME instead of real hardware. It was found to be from MAME based on how the screen was regenerated for each frame. In MAME, each item is placed on the screen piece by piece. On real hardware, the screen is drawn by making a pass across it.
I just find it funny that a 50+ year old guy needs to cheat on a video game to feel good about himself. Steve Weibe pushed to break the record I think just to prove to himself that he could do it.