This was the clip I watched that tipped the scales for me: http://www.youtube.com/watch?v=AHRqH2JTIbw Seems to be a common "springboard" for others as well.
There was no moment at all, I just started to watch (disgusted) the first episode, then I watched the second (confused about myself starting to be crazy) episode, aaaaand, I guess I became a brony at episode 5.
