Did you try setting $use_ssl to 1?
=item C<< get_html( $pubkey, $error, $use_ssl, $options ) >>
On Thu, Nov 7, 2013 at 7:38 AM, Martin Schmitt via RT
<bug-Captcha-reCAPTCHA@rt.cpan.org> wrote:
Show quoted text> Thu Nov 07 10:38:59 2013: Request 90119 was acted upon.
> Transaction: Ticket created by MSCHMITT
> Queue: Captcha-reCAPTCHA
> Subject: Recaptcha hidden in current Firefox because of insecure content
> Broken in: 0.97
> Severity: Critical
> Owner: Nobody
> Requestors: mas@scsy.de
> Status: new
> Ticket <URL:
https://rt.cpan.org/Ticket/Display.html?id=90119 >
>
>
> Firefox does not show the Recaptcha because of its secure content policy. I was able to fix this by changing the API_SERVER and API_VERIFY_SERVER URLs in reCAPTCHA.pm to https.