The reason is simple:

Your ****ty computer has a very small hard drive, so you burn all of your completed .moar files onto DVD. DVDs have limited lifespans, so file corruption sets in early.

This means that while you are pwning fora, you have your chosen DVD in your drive, running that .exec, listening to that .tune, playing that .divy file and reading that .dtbs in the background.

Bruce Bear just happens to sell a powerful DVD-cleaning tool that only works on part of the DVD you have, so you need to buy small amounts of that tool to clean the part of the DVD that the damaged file is contained on. He’s very specific about such things, using a bunch of high tech tools to determine exactly where on the burned portion of your disc the file in question is.

And that’s how it’s done.