Dark0ne implemented the blacklist thing, so obviously this is just a guess but the way I think it works is that it blocks any request with a HTTP referrer header field that indicates that the user came from gmod.com. Thanks for that post, it does clear up some things. However I still think the Gmod people could have thought of the fact that linking directly to the files is going to make a lot of people angry. It's especially nasty for Dark0ne because he misses out on potential ad revenue, but for me as a modder (although I haven't seen any of my files there yet) it's bad because it means many people won't read the mod page which contains important information on how to use the mod. Not to mention the fact that these people probably won't come back to endorse the file. If they would just link to the file description page, it would be okay with me, but I imagine many modders would rather have their mods removed from gmod altogether.