@PitaJ
No worries I can explain:
I've set up a category (Data Technology Team) that I only want one group (NTG Data Tech Team) to access:

I've set up permissions so only group members can access the private category:

I've created a post in the private category and uploaded an image into that post:

I can right click on that image and save a link to it's address:
https://my.domain.name/assets/uploads/files/1445505755666-wa5_dsc30086.jpg
If ANYBODY has that address they can access the picture.
I'd like to be able to tell users that only group members can access that picture, even if an unauthorised person discovers a link to it.
This extra level of security creates peace of mind when posting private material.
I guess it would be nice to have an extra column in the privileges configuration panel that allows/disallows access to uploads associated with each category. That way you can control which group(s) or users can access them.
(I noticed that the nodebb-plugin-poll adds an extra column in the privileges configuration section....maybe a plugin could solve this problem)
Otherwise, everything is perfect!