They do screenshot? Do you have a source so I can read more?

Yes tv makers were caught doing HDMI fingerprinting. There was a story some years ago about how basically all smart tv makers were sending data to an ad network based in China.

Samsung were openly bragging about this on their website some years ago (for the benefit of their advertising partners) but have recently muddied the waters when I check their site again, couching it in language mentioning privacy and other evasive language:

https://www.samsung.com/us/support/answer/ANS10010616/

It's (mostly) a US thing; basically subsidizing TV prices with ad revenue. It's how the entry-level companies like Vizio operate, though the "big brand" TV makers are certainly just as guilty here. It's much less of a thing in the EU, where data privacy laws are stricter and TVs are hence (comparatively) more expensive.

As far as I know, they don't literally scan your media libraries; they screenshot whatever you're watching through HDMI (most often cable / satellite boxes), as those devices don't provide the telemetry that normal apps do. This info is used for audience measurement (thing Nielsen ratings), as well as showing you ads that are actually likely to match your interests.

https://www.ftc.gov/business-guidance/blog/2017/02/what-vizi...

"Starting in 2014, Vizio made TVs that automatically tracked what consumers were watching and transmitted that data back to its servers. Vizio even retrofitted older models by installing its tracking software remotely. All of this, the FTC and AG allege, was done without clearly telling consumers or getting their consent.

...

"Vizio collected a selection of pixels on the screen that it matched to a database of TV, movie, and commercial content

https://arxiv.org/pdf/2409.06203 shows LG and Samsung doing something similar

https://en.wikipedia.org/wiki/Automatic_content_recognition

https://www.youtube.com/watch?v=IvFu343KNek