TVs already do a lot of such tracking, and they are open about it. Samsung famously has their ACR feature[1] which works in a manner similar to what you suggest

TVs already do a lot of such tracking, and they are open about it. Samsung famously has their ACR feature[1] which works in a manner similar to what you suggest - it basically phones home periodically with screenshots of what you're watching. [1] - https://www.samsung.com/us/business/samsungads/resources/tv-ad-retargeting/ https://www.samsung.com/us/business/samsungads/resources/tv-...