Hi. Great plugin. I think the plugin would be far more useful if you didn't make it automatically add the 'http://' to the URI option.
Basically, all that would mean is to change line 80 to:
$redirect_to = ($_POST['redirector_uri']) ? $_POST['redirector_uri'] : $_POST['redirector'];
This way the plugin will work even if with relative links like:
/my-page/my-subpage/