The latest update seems to have successfully removed the msng message I received before, same as adding the custom code did. But it's still not working on yosemite for me (unfortunately I just discovered this workflow so didn't have a chance to test if it worked prior to the upgrade). I'm using the latest 2013 macbook pro retina.
Best I can describe on activating the workflow is it pulls up display, shuffles a bit with the menu and clear selects "Apple TV", but then nothing happens.
Maybe the delay is too short and somehow canceling the menu before it has time to fully implement?