How are the attachment points on top of the camera used?

Toward the front there's a small black rectangle the manual calls a "shoe mount", but it's not like any shoe mount I've seen -- usually they have rails that a flat plate slides under.

And there are two threaded holes further back.Do you need an adapter to use those?

The front one is unlike a still camera hot-shoe, you're right. You can mount 1/4" threaded accessories there and either 1/4" or 3/8" in the rear mounts.
Ed