public function callbackValidVideoUrl($sUrl)
    {
        $sId = $this->blog_post_model->extractYoutubeId($sUrl);

        if (!empty($sId)) {

            return true;

        } else {

            $sId = $this->blog_post_model->extractVimeoId($sUrl);

            if (!empty($sId)) {

                return true;

            } else {

                $oFormValidation = Factory::service('FormValidation');
                $oFormValidation->set_message('_callbackValidVideoUrl', 'Not a valid YouTube or Vimeo URL.');
                return false;
            }
        }
    }