Okay, this is for those who seriously don't understand it.
(I'm using well written grammar and etc.. so it's easier to understand too, LOL.)
When playing an infected game, there's a count-down until when someone gets chosen to be infected right?
Okay, if you get onto the latter, and the count-down goes to 0, and YOU become infected, it actually doesn't show you being infected. You are infected, but it doesn't come into effect until AFTER you get off the latter. So say you are the one that's supposed to be infected and you're on a latter. The game will play as normal, but it'll say nobody has been infected yet and the game won't start/end until the host leaves so the game can end. Notice how when he jumped off the latter, he instantly becomes infected? YERRR.