Here's one: Visual mute. Broadcasters have taking to making commercials "flash" with bright, momentary images, in order to distract/attract attention. When viewing live, I find that the (audio) mute button is no longer sufficient. I'd like the screen to e.g. go 50% gray, where I can still see what's happening when I look at it, but it's no longer distracting me by "flashing" in my peripheral vision.

Given that TV's all have some degree of computerization, these days, I want mine to be open source, for reasons precisely like this.