Add this to the bottom of your .htaccess file:
RewriteRule ^download
\d+)
\d+)/u/.*$ index.php?a=files&s=download&cid=$1&fid=$2&u=1
RewriteRule ^download
\d+)
\d+)/.*$ index.php?a=files&s=download&cid=$1&fid=$2
Then update your templates so that they show something like
/download:$cid:$fid/$filename
this will give a filename like,
/download/123:92/mygame.tgz
which can be friendlier than using stuff like index.php?a=files&s=download&cid=123:92 in shells etc