RewriteEngine on
RewriteCond %{REQUEST_URI} \.(gif|jpe?g|png|mp4|mp3|mpe?g|avi|html?|js|ts|m3u8|m4s|mpd)$ [NC]
RewriteRule ^(.*)$ [WORDPRESS_INDEX_FILE]?grassblade_security_check=1&file=$1 [NC,L]