I have a few stories about this. I came across a video made by an acquaintance on xTube of her using two rather large toys to DP herself. I sent her an e-mail telling her that her video was pretty hot.. but she denied that it was her.
Of course, her face was visible and the username for the account was the exact same as she used for many different sites. She eventually acknowledged it was her video. I felt kind of bad for calling her out.
I have around 10 videos of myself with various women floating around on the internet. My ex-girlfriend's sister ran across one of them and wrote me an email telling me how much she enjoyed it, but I was a little bit creeped out since I hadn't seen her since she was nearly out of high school, so I just said thanks and didn't pursue the inevitable sex that would have happened.
I think some co-workers at a place I worked at in college came across my vids too. None of them said anything at the time, but I heard them quote an exact line that a girl said to me in one of my videos.. and I was always a little suspicious. I also heard rumors later from some of our mutual friends that they saw the clips. I have no way to tell for sure, but I am assuming that they did indeed see them.
I just hope they had as much fun gossiping about me as I did making those videos