> I am insterested in ONE file type in a web site. So in 
the 
> Filtering tab, 
> for example, I type -* +*.mid
> but, to get the whole *.mid files, event the sub pages, I 
> add +*.html +*.htm 
> To stay in this web site, in the Limit tab, I type 0 in 
> front of External 

NO - external depth is only used in last ressort - filters 
are prioritary.

The decision process is:

If filters accept the link, follow it
else, if filters do not accept the link, check external 
depth, and take the decision.

> Do you see something wrong in my options  ?
Use smarter filters, such as:
-* +*.mid +www.yoursite.com/*.htm +www.yoursite.com/*.html

AND NO external depth set!

(BTW - I am also french, I hope you'll understand me :) )