^ what's IWF Picture ME Rollin!
It's the Internet Watch Foundation, an independent bunch of do-gooders here in the UK who want to eliminate access to child porn and other sick material on the net, which is fair enough. But their method is to have ISPs implement a filter which prevents users for downloading from sites, including file share hosts and is completely arbitrary. The IWF basically are relying upon reports of indecent images on sites to add the site to their list and thus blocks users from them while they investigate.
The way it works is that the filter fools the site into thinking it is being flooded by the same IP address thus activating the sites blocking procedures. There is, of course, no evidence that every file is offensive and rather than target the individual file or files, they block access to the ENTIRE site - meaning innocent users are being penalised and the site itself is being forced to lose business based on reports of alleged indecent materials being on there.
Unfortunately while it is a non-profit and independent organisation, they do have UK and European government backing and a majority of UK ISPs are "obliged" to use the filter - mine included. Before you ask, yes we have petitioned them to remove it but they claim it is a "work in progress". In case you weren't aware, UK is supposed to be a democracy - something the IWF clearly has forgotten.
For people like me, it means that we cannot download from file hosts like Filesonic, Wupload, Oron, Uploadstation, Rapidshare and others (some which are very popular on these forums and around the web for J-Idol pics). There are workarounds but they don't work for everyone and the other options are usually expensive.
Obviously we can't dictate to others what file hosts they use but it is a nuisance which is why it's a huge help that (even though it takes longer to download each file individually) that forums like these exists.
Sorry for the long answer but you did ask!
tl;dr version - The IWF filter blocks whole file share sites to stop child porn being seen even if it isn't proven to be there.
*EDIT* - Mediafire is fine btw (for now at least)