> I want to exclude all files that are jpeg and starting 
with
> 't' (e.g. thumbnails) ... i added this to the commandline
> -*t*.jpg

This will also exclude www.example.com/matt/foo.jpg
(because 'matt' contains a 't')

use instead:
-*/t*[file].jpg

If you want to capture all jpg files exept these ones:
+*.jpg -*/t*[file].jpg