Nice, it looks like you got the game sound and voice to co-exist. Bravo on the thorough explanation, even though I know all that stuff I don't think I'd be able to even do half the job you've done conveying it.
The only constructive criticism I can come up with is I don't recall whether or not you went over always coming at the stairs from the north, due to the shotgun angle issues, but I did notice you never came at the stairs from the south. Granted I'm a very negative person, so the fact this is the only thing I can come up is actually a pretty solid endorsement from me. Aren't I pleasant? :)