$other_field = get_post_meta($this->post->ID, 'your_field', true);
            if (!empty($other_field)) {
                $td_post_video['td_video'] = $other_field;
            } else {

                //if it's a video post...
                $td_post_video = get_post_meta($this->post->ID, 'td_post_video', true);
                $td_video_support = new td_video_support();
            }