This movie uses a variety of sequence breaks and shortcuts to complete the game in under an hour using a minimal number of inventory and quest items. Of central interest are the ability to glitch through the Door of Time, meaning that no dungeons need to be entered as young Link, and a memory manipulation glitch known as the Reverse Bottle Adventure, allowing the medallions collected from adult Link’s dungeons to be pulled out of thin air; therefore the only dungeon that is ever entered in this run is Ganon’s Castle.
This run was originally created for the Japanese video site nicovideo, and hence was run on the Japanese version of the game; allowing this is a deliberate exception to the site’s rules. Further improvements are known to exist.
This is now officially the fastest time in the world, though notably this is done with in-game glitches. I must say that I am still rather impressed. This normally goes against the TAS policy, but for some reason they are allowing an exception in this case which only further shows how impressive it really is. You can find out more information at TAS Videos.