Re: Missing the problems of TV GUIs
Sony's Xross Media Bar is an example of a TV UI that is based on what you mention - four direction buttons, [Enter] and [Back] etc. making it suitable for traditional IR remote controllers, as well as Sony's games console controllers. http://en.wikipedia.org/wiki/XrossMediaBar
However, why base a modern TV UI around the limits of these traditional Human Input Devices when touch-screen devices are so cheap? Or indeed 'free' if one assumes the user already has a modern mobile phone (if they don't, what's a £40 Android device to a £500+ TV?). One can then browser the Electronic Programme Guide without obscuring the currently playing programme, or bring up a virtual qwerty keyboard to search for content.
The nicest way to watch Youtube or iPlayer videos on a TV is to find them on a tablet or phone, and them then 'send' them to the TV. If the TV doesn't have this functionality built in, a games console or inexpensive dongle will add it.
Don't get me wrong, a traditional IR remote is good for adjusting the volume or flicking between a few favourite channels, but a touch-screen is better for more involved functions.
Sony will soon be using Android on their TVs, just as LG and Samsung use a former mobile phone OSs on their TVs - Web OS (from Palm) and Tizen respectively. (so I'm not sure who Firefox think they're courting).