A team of researchers has devised a method to defeat NuCaptcha, one of the most popular video-based antispam tests on the Internet. The researchers have proposed a solution to increase its resilience to attacks. The company is also preparing a fix that relies on distorting the shape of individual CAPTCHA characters as they rotate in order to make it harder for the optical flow analysis algorithm to detect them. The solution is called “tracking resistance” and it involves adding decoy objects that have the same properties as the actual CAPCHAs.”]
Source: https://www.csoonline.com/article/2131019/researchers-defeat-video-captcha-antispam-tests.html