Already quite some time ago I was fascinated when I found this video online. Viva la Vida was capturing the world, a song unlike the others at that moment, and then there was this mash-up which for me brought Taylor Swift into my consciousness. Every event that happens changes the world unrecognizably afterwards. This video introduced me and probably many others to The Piano Guys, a concept that has been very productive and copied by others several times over since.
What is your live changing event or world changing YouTube video?