I do but only when wondering how fast someone can beat the game that took me days to finish.
Kidding, I actually like watching speedruns, it's amazing to me how, especially in any% runs, the runners use so many game breaking glitches that need frame perfect inputs and they make it seem like it's the easiest thing in the world. I don't even have to know the game for me to enjoy the speedrun, sometimes the sheer insanity that I witness when watching a runner do his/her thing is entertainment enough.