I'm looking for a fic I remember from a while ago. Dean's watching a vid of a guy jerking off and thinks how weird it is that the guy's so quiet and he realises that the man 'performing' is Sam, who learnt to be quiet sleeping in the same room as Dean & John for so many years. Sam whispers Dean's name when he comes. I'm fairly sure that the fic also had a link to the vid that inspired it, a Sam-a-like (shot so that his face didn't show) masturbating? If anyone can point me towards the fic or vid I'd be very grateful :-)

EDIT; found by an awesome anon! Link in comments.