second will do exactly the same what download.php does (well, almost the same, I skipped header that makes download the image instead of showing it):
http://come.no-ip.com/iguana.php?skip=yes
as u can see in your browser, after image was loaded it shows the direct path to it, no more .php file...
if u use some download managers, then u can easily find out the direct path to the file... 
Well of course if you remove that header you're gonna see the path. That header controls what mime type is returned to the browser. In the case of download.php it's an "application/<browser specific>" mime type such as "application/octet-stream". When you remove it, the mime type changes to that of the file "image/jpeg" in this case.
I've tried the download.php link in an FTP client and the server path was not revealed. I don't have any download manager installed. I also tried using 3 browsers. Not once was I able to see the path.
Can anyone show me a real example of where the path is revealed? Show me a screen shot of a browser, download manager or some other software where it's revealed. Without an actual live example, I'm simply not convinced the path will be known to the end user.
Besides, even if the path IS revealed what's wrong with using .htaccess in the 4images/data/media directory?
# Disable image hot-linking
RewriteEngine On
RewriteCond %{HTTP_REFERER} !^http://(www\.)?domain.*/.*$ [NC]
RewriteRule [^/]+.(gif|avi|mpg|jpg|png)$ http://www.domain.com/No_Access.gif [R,L]
Now the other person can't enter the link to get the file.
Please show me how it's revealed so I have something to examine to think up some ideas.