I just wanted to let all the minibb beta testers know I just release google Captcha support for minibb beta. You can check it out here :)
github . com/tekcomm/minibb-CAPTCHA

miners . biz . tm/images/register.jpg
Registration CAPTCHA

miners . biz . tm/images/post.jpg
Post CAPTCHA

miners . biz . tm/images/goback.jpg
Custom Go Back Button for failed CAPTCHA'S

That sounds very good! So if my brain interprets your code correctly it's used with all users (including logged in members) in topics and posts, when editing a message and when registering a new account?

Thanks but why are you using the version of reCaptcha?

I finally got time to analyze this add-on more deeper, but suddenly concluded the original screenshots provided in the very first post of this thread, are no more available as well as the domain. Be aware of installing something which is out of support.

I didn't check the add-on in action 'cause I have no time to download all those Google keys, but so far regarding this:

I could say it appears to be true. Following the miniBB architecture, this code will appear on each and every page where the posting form is available, and by default it's available on all the thread and internal forums pages. This is sort of painful. Also, it will appear disregarding if the account is being created or registered.