I don't understand it too.
There's this documental if you know jap or spanish (there was an english subbed version but they took it down):
http://www.youtube.com/watch?v=1RXuMCGEfjo
Interesting stuff.
I think one thing is to share content just because you want to and another is to do it for money (like this guy probably did).
Some japs do:
http://www35.atwiki.jp/dldojin/
http://kohada.2ch.net/test/read.cgi/doujin/1322642887/l50
A lot of people here are only for the hentai. I have a HF account made in 2007 (made it to use the search feature) and I've only posted with it like 3 times.
Media Player Classic and Winamp (has never failed me) for music. Sometimes I use mplayer2 in case the playback of the videos isn't optimal or something strange happens.