if( ! function_exists( 'videotube_add_noindex_tag' ) ){
    /**
     *
     * Add a noindex tag once "latest" param found.
     *
     */
    function videotube_add_noindex_tag() {
        if( isset( $_GET['order_post'] ) && $_GET['order_post'] == 'latest' ){
            echo '<meta name="robots" content="noindex, follow">';
        }
    }
    add_action( 'wp_head' , 'videotube_add_noindex_tag',1);
}