If you specify files by *.html it means get any html 
from any site, as the * will expand to for example
www.outsidersite.com/outsiderdir/udontwantthis.html

So if you want files from your original website only, 
you must express all allowing filters (+) as
www.downloadthissite.com*html or any other filetype 
you want.

If you want all, you can just 
+www.downloadthissite.com*