public static function identify_service($url)
    {
        if (preg_match('%youtube|youtu\.be%i', $url)) {
            return self::YOUTUBE;
        } elseif (preg_match('%vimeo%i', $url)) {
            return self::VIMEO;
        } elseif (preg_match('%23video%', $url)) {
            return self::TWENTYTHREE;
        }
        return null;
    }