Can the Apple TV be used as kind of a mobile DVR? I'm looking to be able to bring it with me to my friends house, whenever we want to watch shows, and I buy the shows or content on my itunes account, and stream it to my Apple TV, but not on my wifi. As long as the content is on my iPhone, it can be streamed to the Apple TV, no matter what wifi network it's on? Sorry if this is confusing....