Yeah, the rubber brush sounds like a good idea. Should have tried a gloved hand on it.
It's the material that conected to the body all the way around the door frame except at the bottom. On the bottom there is plastic that is peeling, but that's the owners problem. I don't know how to describe the material type. It's almost like the suede lint brushes and has the same effect of collecting lint, but doesn't really want to release it.
Sorry, no pics at this time. 08 ^ 7 Series.