Have seen it a looooooong time ago. If you noticed Knightmare posted some kind of trailer about assassin's creed back in may. The music of this trailer was from Woodkid. This video is just freakin' awesome (both video and music ofc)
The song was the soundtrack for the trailer of Assassins Creed: Revelations and got famous with that. Clip included. Stays cool though.
<hipster> I saw and loved it before it was cool (aka before that AC creed trailer) 8) </hipster> But I still shiver when I hear it