It's not extra, you'd be replacing the existing window you already look out of.

Either way, windows are not generally the focal point of the room, you'd have an awkward viewing position.

Most likely the sun would be an issue too, the TV picture would only really be visible during dusk/dawn/night.

Also do you have shutters behind the window so outsiders don't see your screen or...?

I don't see any sort of practicality.