I am very interested in speedruns, but especially tool-assisted speedruns. I watch a lot of them, although mostly the popular ones. The most broken the better.
I know some beginner techniques for Super Mario 64 speedrunning, and basically everything there is to know about SM64 TASes.
I also know a few advanced tricks for Ocarina of Time speedrunning, although I can't really put them in practice (do you know just how many frame-perfect tricks there are in the average OoT speedrun?).
Most of all, I studied the mechanics that make it interesting for a game to be speedrun or TASed, and I have been researching game design for games specifically made for speedrunning. Sounds pompous when I put it like that, but really, it's simply about how to reward people for trying to speedrun the game and how to make the experience as enjoyable as possible.
I'm not a speedrunner myself, though I'd like to be. There is too much work involved though, and I don't have the mental or physical capacities to output this much concentration, dedication and reflexes into something. Same reason why I'm not a pro competitive player.