How do you get the one Metal Gear Solid music track - you know, the one that plays at the end of the one level where you go up the long elevator? (I think it's Act 4). At first I thought you just couldn't get this music, but then I noticed it playing in a custom level online. So you must be able to. But I've collected 100% of the MGS items and I don't find that music track in my inventory. What's the deal?