About the automatic background images, it's cool to see an image from the movie you are reviewing, but I imagine it's heavy in terms of performance.
Probably a background that can be changed from the Album or another source on the phone/tablet is a better option? If a live wallparer is too heavy, then probably a list of pictures that are scheduled to change in a specific time? With a transition effect of some kind.
About the chromecast like functionality, I really don't know. I never used that device and don't know how it works. I did noticed an app for Samsung TVs that was something like the ServiiGo, providing the content using a beautiful GUI. I don't remember what the app name was, if needed, I'll look it up in my TV.
So, the app is based on the server-client model and needs a PC that provides the content to the TV app. It's of course device specific, but one of the pros would be using the remote control that came with the TV.
I can't imagine how much hard work that would need, not to mention approving the app in the market. But on the other hand, you can put a price on it and I'm sure there will be quite a lot of people byuing it, as I am not aware of much alternative apps out there
