htaccess protect pretty url with password

.htaccess

# Do the regex check against the URI here, if match, set the "require_auth" var
SetEnvIf Request_URI ^/admin require_auth=true

# Auth stuff
AuthUserFile /home/juarain/.htpasswds/admin/.htpasswd
AuthName "Password Protected"
AuthType Basic

# Setup a deny/allow
Order Deny,Allow
# Deny from everyone
Deny from all
# except if either of these are satisfied
Satisfy any
# 1. a valid authenticated user
Require valid-user
# or 2. the "require_auth" var is NOT set
Allow from env=!require_auth