The first one was definitely the better of the two, but it's interesting and well-made.
In the first one the side-banter was interesting and clever (the "this requires serious music" comment was amazing). The reason it played out so well, though, is that the rest of the video was serious. In the second one the narrator is frequently cracking jokes, or making asides, and it works against both the moments of humor and the moments of seriousness. Keep things tense when you can, feel out when to toss in an aside.
I feel that the mix of the Grindhouse and Zombieland vibes also play to the strengths of the short, and the "Would you like to know more?" reference to Starship Troopers played out amazingly, almost like an alternate timeline in the same universe. The Scott Pilgrim "Pee Bar" moment, however, fell flat to me. If you're going to include a statistical/video game-y vibe, own that early and often, and not just to crack a joke (see the above paragraph for my explanation as to why).
All-in-all, very well executed. I'm looking forward to seeing some more of these, and will definitely be showing some friends.