The presentation takes a while to get around to it, but it's a way to see your browser history using cert pinning/redirection. Specifically (ab)using features in the browser that even the paranoid don't disable. And then using that information to fingerprint you.

Demo: http://zyan.scripts.mit.edu/sniffly Code: https://github.com/diracdeltas/sniffly

It's a good find, even if it's not perfect the way the CSS link visited computed style checks was.