I need to rewatch it to find a couple specials..
While there are a couple rough spots, it's overall a very good little video and I'd love to see a continuation of this. the characters (based on real people or otherwise) are compelling despite my not knowing anything about them. The connectivity of them feels real despite such a connection only being briefly hinted at.
Even if it doesn't quite catch the grim, doomed flavor of Left 4 Dead, I still feel this is a suitable contribution as this is not L4D 3 or anything. This is your interpretation of your friends in the face of disaster. Even if the world is heinously fucked, you seem as a group to pull together as a sort of family- which is kind of the main theme tugged at with "The Sacrifice", the latest DLC for the L4D series.
The point I'm getting at is, don't worry about the "THIS ISN'T L4D" comments below me. They're just being stuffy and picky.
Given the charm this video has, I'm willing to give this a 10. Is it perfect? no. But nothing is, and this has heart and warmth for days- despite the whole zombie apocalypse thing. =)
10/10, 5/5.