The one thing that determines whether a video will be viral or not is whether after watching it, your jaw has dropped. It doesn't matter why your jaw will have fallen open-- it could be from laughter, shock, awe, or even anger. All that matters is that you have to see it again to be sure of whatever it is you've just seen. I had that experience with this screen test video. Upon watching it, I was filled with such a sense of WTF that I fell in love instantly.
The set-up is simple, right? A Russian-sounding guy is auditioning for a commercial. There is nothing out of the ordinary about that, but every other aspect of this ad is extraordinary. Let's start with this guy's outfit. He's auditioning for a role as what seems like the Gorton's fisherman, but he's dressed more like The Undertaker. Is Paul Bearer his agent? He's reading for this commercial, but it sounds like he's never seen the script before-- like he just happened in on the way to the bathroom and decided "What the heck? Today, I'm an actor. What a country!" The best part, though, is that there are these key phrases that he hits that would sound like regular advertising copy if it had been read by anyone but this dude. "Specialty seasonings." I want him to sell everything.
It's such a simple set-up, and that's what allows it to be so amazing.