Allan “dwangoAC” has made it his mission to expose speedrunning phonies. At the Defcon hacker conference, he’ll challenge one record that's stood for 15 years.
If you find the article interesting, the technical analysis of the speedrun is here and worth a read. https://diablo.tas.bot/
I watched a youtube video once that they figured out the guy was cheating via Mario's eye blinking pattern. Good for them I say. I'm not a speedrunner but I love watching speedruns and it's really really lame if you're cheating. Just get good.