Thanks for the follow up but Miles is correct. Even though I can set one specific client for the Virtual Channel using Channel Collections the content within that channel is still accessible by the other clients. For example, I uploaded a video clip and created a test channel. I then created a channel collection with this test channel. The collection only shows up on my phone (as I set it up) but the content of the channel showed up in the, "HD" preset Channel Collection. I would have to delete, "HD" on every client to restrict them. If it were a movie I would have to delete, "Movie" as well. This is a function of how well you designed the channel collections to aggregate content so it's understandable but hinders this use case.
So I'll ask again as a feature request to restrict Virtual Channels (and their content) to specific clients? It may not be possible (and that's ok) but I would find it useful. And perhaps others would as well.
Awesome service - keeps getting better!