NuCaptcha is a video CAPTCHA service that uses video and rotating text to make CAPTCHAs easier for humans to read than most standard CAPTCHAs, while maintaining a high level of difficulty for automated systems.
In order to use NuCaptcha, you will need a client key from their website and be running at least PHP 5.1.x (5.3.x for Windows) with the mcrypt extension enabled.
