Thanks for the explanation, that does make sense. I'm probly the odd one out in that I use a separate dedicated browser for porn (Opera) in which I've never logged into any google, amazon, facebook, twitter, etc service. Just my porn subscriptions and a couple of porn forums. It's not that I really care about the tracking, its just I find it nice to be able to have open tabs and bookmarks organized for my porn without cluttering up my other browsers I where I work and play.
That said, re the topic at hand, I don't think I would ever want to watch porn with other people unless it was like a significant other. Honestly, it sound like a virtual circle jerk, not my kind of thing, but that's cool if other people are into that. I like to feel like I am the only person in the world watching a video, like that video was for me and it is just me and the girl, it's our little secret.