When I originally tried this I was getting rotation on two axes, not just the one I wanted.  Has anyone else had that happen?    The object did rotate around its center of origin, but on two axes, not just the one (It maintained it's orientation to the camera but rolled like a wheel as the camer panned acroos it). 

(Assuming the camera is just moving laterally, the object should pivot around its Y axis.  Moving the camera up and down would naturally rotate the object around a second axis.  This is not what I was getting.) 

I'll try using a dummy, but I'm not sure which object needs to point at the camera with that method.