Well, this glitch is about 3-4 weeks, old. This may have probably been a great discovery for you, but the host might have lag switched for you or something and KA-BOOM you are up there alone in the pack-a-punch. The zombies can still get you if you are the last one alive because the zombies will run and climb up those stairs for you. So, you better have good teammates when you are doing this. BTW I believe there are a couple of Threads on this website that can show you how to do this glitch on XBOX 360 and the PS3. So, thanks for posting this Thread helpful to many new people who haven't seen it yet and most likely will search it up in the search bar for how to do it.