> Now to my question, is it possible to do a 
bot/spider/robot 
> like download, like all 111111111111111.jpg to 
> zzzzzzzzzzzz.jpg? this would result sooner or later in 
> valid links/jpgs, would take some time...

Hum, no, because:
- it would require too much time (decades..)
- it would be considered as VERY impolite by the webmaster 
of the site (generating thousands of error logs)

The only solution is either to find a page which references 
all links, or ask the webmaster for having access to the 
files.