Most of these answers are how it *used*to work. Not anymore. SmartTVs changed that. Something like 25% of devices now scan the images on the screen and “capture” what youre watching. For TVs using Roku, AppleTV, Fire stick, or Chromecast, those vendors have…interesting agreements about what they can or can’t know about what you’re watching from an app perspective.. with YouTube tv, Hulu, sling, all bets are off. Nielsen used to have free rein here, but no longer. 2017 Congress started letting internet providers sell info about the data being consumed in your home. For tv that’s easier than you think because all cable boxes are digital now. And that’s why Comcast, at&t, verizon, etc became advertising companies AND their own networks. At&t buying HBO etc.
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