if( ! function_exists( 'videotube_child_reorder_category_videos' ) ){
    /**
     *
     * Reordering videos
     *
     * @link https://codex.wordpress.org/Class_Reference/WP_Query#Order_.26_Orderby_Parameters
     *
     * @param $query
     *
     */
    function videotube_child_reorder_category_videos( $query ) {

        if( $query->is_main_query() && $query->is_tax( 'category' ) ){
            $query->set( 'orderby', 'post_title' );
            $query->set( 'order', 'ASC' );
        }

    }
    add_action( 'pre_get_posts' , 'videotube_child_reorder_category_videos', 10, 1 );
}