NuCaptcha is a world’s first video based Captcha service that uses motion video to authenticate human web interactions. It is one of the best solution compared to image-based captchas, because it is displayed in video format which is harder-to-recognize for bots and can be read easier by humans which is great.
The service is a very easy to use and absolutely Free of cost. With NuCaptcha Basic you can choose one of several themes that best fits your preferences or website. Even you can customized your captcha Skin, background and message displayed in Flash videos which helps a better visual integration with the websites.
Download : NuCaptcha