Guys where is the code that redirects users to captcha after they have entered wrong password/username X times?
Member.php at around line 1173
Search for
if($mybb->settings['failedcaptchalogincount'] > 0 && ($loginattempts > $mybb->settings['failedcaptchalogincount'] || intval($mybb->cookies['loginattempts']) > $mybb->settings['failedcaptchalogincount']))
if you can't find it.