0xxx describes itself as being the 'best 0 day porn source'. What is 0 day? Well, put simply, it's when porn videos are published for the first time and they get shared around the web.
Now I'm going to be up front here: it looks a hell of a lot like 0xxx takes clips from paysites and stores them on an external file host for people to download. Now there are legitimate reasons to do this (reduce bandwidth, offer mirrors, etc.) but there are a few illegitimate reasons too. I'm hoping that anyone using this site has full access to the original paysite they came from! Let's not forget to pay for porn.
Anyway, new scenes are added on a daily basis and are done so in a range of qualities, though most are either 720p, 1080p or 2160p. Sites include Deep Throat Sirens, This Girl Sucks, Fucking Machines, Digital Playground and a whole host of other noteworthy paysites. All clips come with a screencap display and multiple download links so you can get them from a number of sources.