Dishonored co-directors Raf Colantonio and Harvey Smith are serious guys who make serious games, but in the above video we see a different side of them. The three minute long, heavily edited walkthrough plays like an E3 walkthrough gone wrong: The two make up things about the game, spout nonsense, and disregard the elements that usually would be the focus. It's pretty funny, especially when you imagine it's really just the result of E3 and after parties wearing down on them on the final day. I think we've been in a similar state before (see: E3 Podtoid episodes).
I always appreciate a good April Fools joke that I can post and laugh at, without thinking in the back of my mind, "Oh God, what if this is actually real and I just greatly offended someone!"