Metro 2033 - Out of Map Bug on Depository

This is a pretty common bug, it happens on the level Depository in Chapter 5. After the cut scene where the librarian smacks you on ground, you fall through the floor unto the map outside and you are able to walk it. It doesn't happen with everyone but with a lot of people. And the only way to bypass it is to walk around the wall with the librarian. So don't worry I didn't get stuck in the campaign. I am aware there are a lot of clips of this glitch out there already but I'm pretty sure I'm the first one with that librarian in that staircase with his ass wiggling. If you don't know what I'm talking about, watch the video, and laugh. :)