What exactly do those do? I'm guessing they are homemade dubbing brushes or something?
They do the same thing a dubbing needle does only on a larger scale. After you tie a fly or jig with a body made with dubbing, you use the Velcro to brush the dubbing and it pulls the little fibers out making the fly look really buggy, dubbing needles are nice when you want to do just a small portion of the body or when you only want it to be a little buggy, but those little tools work great if you use dubbed bodies a lot.