It seems like the record Billy is most proud of is his perfect game of Pac-Man. (To this day on Twitter he calls himself "Pac-Man Billy.") Here's a good article that explains how difficult that was.
https://www.oxfordamerican.org/magazine/item/622-the-perfect...
After 254 levels of normal Pac-man, the screen fills with jibberish and screen noise -- some of the pixels you have to eat are actually invisible. Billy was the first person on planet earth to crack that level.
That's one of the other records Twin Galaxies has invalidated.
Billy's argument is in part: there's zero evidence he cheated at Pac-man, so why is that score being invalidated too.