Tools Assisted Speedrun (TAS):
Legend of Zelda: Majora's Mask TAS in 1:29:32 by MrGrunz
Majora's Mask is often considered one of the more entertaining speed runs of a 3D Zelda game, the action starts off pretty slow but once he learns the Song of Healing that is when the action starts to really shine.
This TAS of the game is the result of three years of hard work and many restarts due to new discoveries. It features many never-before-seen tricks and glitches, and completes every dungeon without getting a single boss key. Everything is done out of order, in ways that will amaze the viewer and keep them on the edge of their seat the entire way through, including a whole new way of warping between the areas in the game's over-world, and a new method of traveling that makes even the longest stretches in the game seem tiny.
Because of this, it beats a nearly 4 year old TAS run by just under 45 minutes!! It is also currently rated with a SPECIAL STAR meaning it's an incredibly high quality run in both technical and entertainment.
Funny thing is that one of the new tricks is not discovered by me but someone I don't know personally who lives pretty nearby :o
Real time (not Tools Assisted) speed run:
The Elder Scrolls 3: Morrowind Speedrun in 4:19 by Jānis 'Pendrokar' Lukss
It's pretty suprising how an open world W-RPG can be cleared in less than 5 minutes. I personally love older game engines too because the flaws are usually abusable and useful too. One of the early spells you get in the game enables the player to jump across the map for 7 seconds. Jump as soon as possible and hopefully land before the 7th second otherwise you'll take major fall damage. Raise the brightness up on your PC monitor if you find it hard to watch the dungeon segments because of the dark colours.
Loads of tricks like 'constant item attribute bug' and using the 'harmful weapons' safely are explained in this page: http://speeddemosarchive.com/Morrowind.html