From google faq
Code:
localhost domains are no longer supported by default. If you wish to continue supporting them for development you can add them to the list of supported domains for your site key. Go to the admin console to update your list of supported domains. We advise to use a separate key for development and production and to not allow localhost on your production site key.
developers.google.com/recaptcha/docs/faq
Because some ppl still think we are just making it up