Now that Dishonored is here, most of the videos you're going to see will be folks showing off their experience on Youtube. There will be folks showing off glitches where a character's arm/head/shoulder/boot is sticking into or out of a wall/donkey/candelabra in a way that looks funny. There will probably be videos of people finding the coolest whatever in some some super secret hidden yet obvious place. Community videos like that are very important and should help enhance your experience if you've already got the game.
However, this launch trailer for Dishonored is intended to make the final case and appeal to your sense of adventure/duty/guilt to pick up your own copy. Seeing a fuzzy unicorn breakdancing video from Dishonored online is only cool and popular if you're already playing the game and into what Dishonored has to offer. This trailer is supposed to get you over the hump so no unicorns for you yet.