So recently I've really been getting into watching speed runs of games. A part of that is the "Awesome Games Done Quick" charity marathon put on by Speeddemosarchive.com and speedrunslive.com. It's a 7-day marathon to raise money for cancer, and AGDQ 2013 (in January) raised $448,423.27.
What I love about AGDQ is that the runners and other people tend to explain the glitches and tricks and their genesis.
So to get this started, here is a couple of runs I found absolutely amazing:
Zelda: Ocarina Of Time Any% in 22:38
Super Mario 64 120-Stars in 1:47:48
Super Metroid Any% in 49:35
Here is a link to ALL of the videos from AGDQ 2013:
TAS: Tool-assisted speedrun - using a program or tool to help the runner. All the AGDQ runs are NOT TAS.
Any%: Means any % completion. Usually just the fastest way to see the credits.