• Unique Value Proposition
• Return Visits
• Time Spent on the Website
• Few (apparent) out links

Unique content is a factor but how well is video content indexed by GôôgleBot? It's the tube's page text creating the SERPs in it's ranking of the above 4 items.

• Unique Value Proposition

  I can fap for free here, or;
  this porn site has something worth paying for so I have to pay to fap here.

• Return Visits

  I can go back and fap free, or;
  I am paying to fap here I want to get my money's worth.

• Time Spent on the Website

  I like to fap here!

• Few (apparent) out links

  Lots of stuff to fap to on this domain I'll post links to it on my Facebook, Twitter, other page -- real inbound links

Cookie cutter sites and link farms have been dead for sometime now.

Affiliate sites have to have an angle, usually some editorial comment or affiliate created content. Captain Obvious has spoken :P but to many these points get lost apparently -- hence the BWAH! GOOGLE posts ...