[TimothyBurgess]

That's very interesting.

I just checked it out for a couple of minutes... And what's even more interesting is that when you were browsing HN my browser had obviously loaded it as if I were browsing. (We definitely saw 2 different things... My guess is that you record mouse coordinates, scroll positions, and url changes.) With that said, I could see this as a potential security risk - unless there are protocols already in place of which I am unaware. I was curious to see if you'd start typing or post a comment or something but I didn't stick around long enough. I think browsers natively have measures to prevent security breaches like this but I wouldn't be surprised if there's a way around it.