if( !function_exists( 'mars_get_total_views' ) ){

    /**
     * Get total view count
     * @param string $post_type (video or post)
     * @return int
     */

    function mars_get_total_views( $post_type = 'video' ) {

        global $wpdb;

        $query = $wpdb->get_var( $wpdb->prepare(
                "
            SELECT sum(meta_value)
            FROM $wpdb->postmeta LEFT JOIN $wpdb->posts ON ( $wpdb->postmeta.post_id = $wpdb->posts.ID )
            WHERE meta_key = %s
            AND $wpdb->posts.post_status = %s
            AND $wpdb->posts.post_type = %s
            ",
            'count_viewed',
            'publish',
            $post_type
        ) );

        return (int)$query > 0 ? $query : 0;
    }
}

echo mars_get_total_views( 'video' );

echo mars_get_total_views( 'post' );