Killing 25 enemies in Dishonored apparently without breaking a sweat is impressive, but what Youtuber kekkoSoNicSyNdIcAtE does to that guy's body at the end just pushes this over the top. Now you're just showing off, bro.
Dishonored provides players with a lot of different ways to complete goals. Many of those ways happen to involve killing people. And this player has mastered pretty much all of those.