In December Google introduced their new system, claiming to be more robust to bots. But their new system is like you don't anything on your site.
Everything looks good in the video
Their new anti-bot system works simple. The first time you visit a page (see here an example), you will be asked to write something. The next time and because you already proved that you are not a bot, you don't have to write anything, because reCAPTCHA stored a cookie into your PC, that "tells" Google that you are a human. If you delete this cookie, you have to repeat the process.
The problem is that what Google does with the cookies, can be done from the bots, too, as Homakov says. Homakov uploaded an html code that shows us how easy is to bypass the new version of reCAPTCHA.