YouTube is excited about its active sharing feature that lets YouTube watchers signal to other viewers when they are watching a particular video (if you turn the setting on, anyone watching the video at the same time as you will see your username on the right side of the screen). When you start ActiveSharing, your username will appear to other users on the videos you watch. A list of videos you’ve recently watched will also appear on your profile page.

This reminds me of the javascript code snippets that anyone can insert in their blog code to show every visitor on your site who visited your site from Blogging communities such as MyBlogLog and BlogCatalog.