Abstract: An automated method performed by a content host computer determines whether a client user is a human. A request for access to content residing on the content host computer is received from a client user. One or more advertising video clips are presented to the client user. An entire authenticating reference pass phrase is communicated to the client user in exactly one advertising video clip. An input passphrase is received from the client user. The input pass phrase is compared to the authenticating reference pass phrase. If the comparison shows identity, the client user is granted access to the requested content.