.htaccess login

Dear author of this great script.My congratulations!!!
I have a little problem.I would like to restrict access for downloading zip archives from my site (I think I'll use your script) by means of .htaccess file like this.

AuthName "Only valid users can download zip files"
AuthType Basic
AuthUserFile /home/mysite/www/dr/.htpasswd
Require valid-user

It's works (separately).

But with your script it doesn't work (I think reason of this is this type download link:

http://mysite.com/main.php?cmd=image&var1=nature%2Fmyfile.zip
)

I need your help.How can i change this
http://mysite.com/main.php?cmd=image&var1=nature%2Fmyfile.zip
with something like this:
http://mysite.com/folder/myfile.zip

Thank you