First, some background. OOT speedrunners make use of a Stale Reference Manipulation (SRM) called Lightnode SRM to alter the game's code and memory through specific characters in the save game's filename. Such manipulation makes the end credits roll after the player completes a series of specific inputs in the opening Kokiri Forest section. It might not be the full-game experience, but hey, that's an Any % speedrun.
Typically, the Wii's Virtual Console has been the platform of choice for this as it was allowed via a bug in its N64 emulation. However, a speedrunner with the rather excellent title MrCheeze has recently discovered a filename that works for the Wii U, making use of the console's improved framerate to shave seconds off.
"Okay," you may be wondering, "where does the rubber band come into this?" Well, we're getting to that. You see, the Lightnode SRM requires extremely precise button inputs, with the final move being holding the joystick at a Y-43 angle. Working with MrCheeze, another speedrunner called bradyONE realised that the best way to hit this angle first time is to hold the stick in place with a rubber band.
Normally, doing something like this would disturb the entire run — after all, there's still roughly four minutes of gameplay required before hitting this angle — but this is where the Wii U GamePad comes into its own. Remember that mostly useless 'TV Remote mode' that would turn your GamePad into... well... a TV remote? It also limits button inputs from the device, so you can strap the stick in place, flick on the remote mode, start the speedrun with another controller and then deactivate the mode to let the GamePad bring things home with the final input.
Here's bradyONE showing the method in action:
Genius, right? Well, maybe not quite. Current Ocarina of Time speedrunning rules stipulate "You are only allowed to use one controller with one analog mapping per controller port," meaning "you may not switch controllers, switch mappings, change calibration, or toggle on/off calibration or mappings during your run." Bummer.
The question is, does the GamePad's TV Remote mode really count as switching controllers, or is it just making the most of the console's input settings? That's what the speedrunning community is going to have to decide now. Either, the technique is too close to the wire and it will be disallowed or you're gunna need to break out the rubber bands for future speedrunning attempts.