I think he was referring to self-signed certificates, which you can create yourself.
These certificates causes your browser to display a warning (and Firefox warning is pretty dissuasive), because they aren't secure (they're vulnerable to man-in-the-middle attacks).

StartSSL "class 1" certificates, albeit free, are signed by a Certification Authority (StartCom), and display no warning in your Web-browser. (They aren't vulnerable to man-in-the-middle attacks).