So is any criticism going to result in the dreaded "epic fail"? Maybe they're not elitist, maybe it's just not a very good video?
Here's why: The topic suggests (perhaps humourously) that it should become an official trailer. It would not make a very good trailer, since it's doesn't address much of the game other than gibbing zeds, and there's lots of games with monsters and gibbing. A lot of the draw, for many of us, is the co-op action, teaming up with people and fighting off waves of stuff that would normally kill us, tear bits off us, and smear us all over the metal plates inexplicably bolted across their mouths.
How to improve it? Don't try to sell it as a trailer, sell it as "Look, a bunch of zombie gore explosions!" also, it would help if it was edited a bit more. Sync up the action to the music, so what's happening on screen corresponds to the highs and lows of the song. Maybe skip Ave Maria for something that evokes the same feeling, but isn't so horribly overused. (Unless overused is what you're going for? With the "boom headshot" thing. Maybe this is just a troll and I'm too dumb to ignore it?) Edit out the parts that aren't cool or epic or whatever, like standing there reloading while some zombies swat at your face. Stitch it together so the player (= viewer) is a total badass that's effortlessly wading through knee-deep blood as he executes those he finds disfavour with.
And not taking it quite so personally could help.