how can I tell what packages depend on group memebership?

[Nano Nano <40101.nospam@comcast.net>]

Greg F. recently said he adds all console users to the groups:
audio, video, floppy, cdrom.

I'll probably add my users to audio, for sure.

I'm trying to decide if I should me to the other groups:

I use my webcam safely without being a member of the video group.
My non-cdrom users can mount cds but cannot rip or burn them.

So is there a way to tell what behavior depends on being a member of 
what groups, by querying the package database or something?