http://speeddemosarchive.com/ is a site dedicated to maintaining videos of world-record video game completion. Do you want to see how to beat Legend of Zelda in 30 minutes or less? This is your place.
Anyway, the speed-runner leave comments about their videos, which explain what they did to make their run the fastest. Many of them spend months in preparation for their main run. The interesting thing is that it's not just for achievement. People go to the forums there and post bounties (cash rewards) for speed runs they want to see, or challenges they want to make. In other words, beating video games quickly is now a professional sport!
Anyway, it can't be too bad, because it spawned
this.