This is a whitepaper about breaking reCAPTCHA along with the presentation given at Defcon 18 (showing how the author broke it a second time right before the conference). There is also the word list included that was used for the crack and a video demonstrating this in action.
You can download it from the following link: https://packetstormsecurity.com/files/download/92524/recaptcha-broken.tgz
Source: https://packetstormsecurity.com/files/92524/Defcon-18-reCAPTCHA-Broken.html