[TYPO3-english] DAM and file access permissions for fe_users

[Martin Mädler]

Hello List,

I'm using TYPO3 4.5.3 and Media (DAM) 1.2.2 - Digital Asset Management - 
to manage my files. I want some files to be accessed only by specific 
frontend users (fe_groups). To be more specific: a given link e.g. 
www.example.com/secured/test.pdf should only work if you are logged in 
as a frontend user with the appropriate access rights.

How can I do that?

What I tried:
When I open the DAM interface from the backend and go into edit mode of 
a pdf file (for example), I see the following options:
Access: Hide (checkbox) - Start (date) - Stop(date)
Access: Selected Groups (fe_group)

But this has no effect whatsoever on the availability of said file 
(cleared cache). What purpose do these options serve? Do I miss 
something? I wasn't able to find it documented anywhere.

Thanks in advance
Martin