It looks good, and don't want to shoot down the UI, but here are some suggestions: In regard to pictures 4 and 5, Roku tried the fully horizontal menu for a while, but wasn't great. It's too limiting. Think about using a vertical left and a grid right like they do. It fits more and given the right control, works pretty well to navigate, even if it isn't the prettiest. And, if you only do one thing, remember the rule…
While grids are nice they have a problem. They're great at navigating two dimensions but they aren't easy to get out of. Where do you put the settings and search buttons? Do I have to scroll through all the categories (like netflix does) to get to search?
Similarly how do you do subcategories?
This system actually solves both of those problems. What it lacks is information density. Something like this linking _into_ a grid could work.
Note I say this while our company that does this developed an app with this exact navigation scheme for Comcast cable boxes.
http://adifferentengine.com/cases/sochi/
But we had a very strict set of content so we knew it would work for our use case.