Where Do Filehosting Site Get Contents Now Adays?

I used to remember leeching and using the url upload of xfilesharing scripts from megaupload premium but now adays when mega was already out. Where do this filehosting sites gets there content using the url remote uploads? or do they do it manually now?

 

I honestly think the majority of filesharing websites just get their content from torrents and whatnot. Some might do it manually but I doubt it.