Why the FUCK can't I be this good. This dude is the first one to beat Doom on Ultra Nightmare mode. He makes it look so damn easy too. Keep in mind that if you die one time in this mode you have to go all the way back to the start of the game.
>that target prioritization
>that target acquisition speed
>that gun selection accuracy and speed
>that carefully planned character movement
That player knows the game inside and out. I would be surprised if it wasn't someone involved in the game's development. They knew spawn locations, secrets, ammo and upgrade drops, where enemy fire would be coming from, etc. If they weren't part of development, they played that difficulty level a lot to get that experience. Fun to watch, though.