Good stuff.
I have to admit, I was a bit discouraged after seeing Left 4 LOL that there would be any more L4D parodies that would be humorous. I took a quick read of your comment before I played it, and I have to say, for your first submission, it's pretty damn good. Animation isn't anything stellar, but it is solid. Nice use of the voices from the actual game in your flash. The only real problem I have is the humor of it. Some of these are pretty clever(personal favorites are when Louis gets drugged after getting mauled by zombies making him see a zombie as a mildly hot woman as well as the safehouse one with no smokers or fatasses allowed), and the rest at least put some kind of grin on my face, but that's it. It's good that you steered away from the usual "cockjoke extrodinairre", but some foul humor here and there wouldn't be too harmful now, would it?
Other than that complaint, I like it. For it being your first submission to Newgrounds, I can see you're going to have a bright future ahead of you.