If you haven't seen Dr. Horrible, don't just watch some random clips - watch the whole thing, start to finish. Its like 40 minutes and change, so just watch it. Its worth it.
What's wrong with us is that our humor centers were calibrated differently than yours. Thus, we find this funny. You, on the other hand, like fart videos and videos of dogs doing pwecious things.
I want to have a threesome with Nathan Fillion and Neil Patrick Harris, but they have to earn that by serenading me first with their wonderful capacity for song.
Dr. Horrible is pretty damn awesome. And that's from someone who loathes everything else Joss Whedon has ever done and every other role Nathan Fillion has ever been in.