"Whatever the user-defined filters are, the engine 
will always put DEFAULT filters. 
For example, if you crawl www.foo.com/bar/index.html, 
the engine will automatically add the filter 
+www.foo.com/bar/* before all other filters"

from what i understand reading xavier's comments, 
httrack's default filters (i.e., when you don't enter 
any custom filters) are the url(s) you enter + '*' -- 
now the question is whether '*' means just html files 
or all files. my hunch is that the engine follows the 
primary scan rule in the 'experts only ' tab, which 
defaults to "store all files".