Aprenda como modicar o endereço da pasta de mídia do Wordpress.org

.htaccess

RedirectMatch 301 ^/wp-content/uploads/(.*)$ http://midia.seudominio.com/$1

mudar-diretorio-de-midia-wordpress.sql

UPDATE wp_posts SET post_content = REPLACE(post_content,'http://www.seusite.com/wp-content/uploads/','http://midia.seusite.com/');

UPDATE wp_posts SET guid = REPLACE(guid,'http://www.seusite.com/wp-content/uploads/','http://midia.seusite.com/');