> so if i want to download only JPG on a web site who have 
> Lot of .mpg i have to download all .mpg too ?..........

No you don't have to.  Sorry, I should have mentioned some 
filters to use.

If you know ALL the types of files you DON'T want to 
download, add filters (scan rules) like:

-*.gif -*.mpg -*.mpeg


If you don't know them all but know which ones you exactly 
WANT, you can try something like:

-*
+www.website.com/folder/*.htm
+www.website.com/folder/*.html
+www.website.com/folder/*.jpg