Controlling access to attachments

[ncg]

We have a paid website and a free forum. Currently forum members and forum guests have permission to see and download all attachments. We encourage members to post some of our website content in the forums but do not want to be giving away paid content for free so we want only website members to be able to access the attachments themselves.

So we'd like that forum members and forum guests are allowed to see the thumbnails but only Website members have access to the actual attachments. I know that we could do this with IMG & URL links rather than the attachment function but it presents a problem.

1. Posters will have to source or create their own thumbnails. They could source thumbnails from the members area of the site but they are currently stored in a DB and are referred to in the following format, which doesn't display as a thumbnail in the forums - http://domain.com/media.php?id=134519

Short of integrating the seperate website and forum accounts into single accounts is it possible?

I thought that putting membership restrictions on the attachment directory would be the easiest way to go but this will also restrict access to the thumbs wont it? We would like the thumbnails to be visible to all.

Is there any quick and easy way to do this? Can we put the membership restriction on that directory but exclude any of the .thumb files? Will that work?