Connect the camera to a new GameObject and add to this gameobject a script with:

var follow : Transform;

function LateUpdate() {
    transform.position = follow.position;
}

next, in inspector of the gameobject, set follow to the rolling rigidbody instance (just drag it from scene view to this property).

that "Empty GameObject Trick" is like this..

var targ:Transform;
var offset:Vector3;
function Start(){
offset=transform.position-targ.position;//init offset at start
}
function Update(){
transform.position=targ.position+offset;
}