Perhaps try this one?
^/2008/films/ /2008/films.php [L]
I added a slash before the first 2008.
If you are really having trouble, consider turning on the RewriteLog and you can see what sort of comparisons are actually getting made. NOTE: this doesn't work so well if you are working on a busy machine.
Also, I can't help but wonder if your RewriteRule exists in an .htaccess file or whether it is in the apache configuration folder. If it's in an .htaccess file, you may need to put an AllowOverrride directive in there for your new folder:
<Directory /path/to/dir/named/2008 >
AllowOverride All
</Directory>