There are a few styles of competitive video gaming out there. Most gamers are familiar with the head-to-head stuff like Starcraft tournaments and have become aware (thanks to movies like King of Kong and Chasing Ghosts) of the folks who spend months or years trying to set a world record high score in their chosen arcade games.
Another, lesser-known competition exists as a genre called speedrunning. The concept is to complete a video game as quickly as possible. This includes finding the optimal paths through levels, figuring out any predictable patters the stuff in the game is going to take, coming one hit or a pixel shy of screwing the challenge up, and exploiting any bugs in the games that allow for shortcuts. If you were frustrated with a Nintendo game growing up, there's something satisfying in watching somebody blow through it in a matter of minutes.
Summer Games Done Quick 2012 is a marathon event of speedrunning that's currently taking place (finishing May 28th) as a fundraiser on behalf of the Organization for Autism Research. They've run a few of these Games Done Quick events before, and what's great about them is you get to watch the games and the crowd playing them (occasional commentary on speedrunning techniques, cheering on wins, oohs and frustration on failure) and maybe relive a little of your misspent youth. They even do head-to-head competition on some of the games.
I should mention that I am completely unaffiliated with the event and the charity, but have become a fan of Games Done Quick over the last couple of events they've held and think it's totally worth checking out for any video game enthusiasts. The site they're running on, Speed Demos Archive, also has a trove of other speedrunning videos if you have a specific game you want to see won in the quickest possible manner.