How did Parrot Analytics measure viewership if users used Apple TV app?

Some “smart” TVs transmit samples of video from HDMI and streaming inputs to the TV manufacturers, who sell it to third parties and use it to target ads. Samsung is arguably the worst example. From https://www.samsung.com/us/account/privacy-policy/:

“We may use automatic content recognition (ACR) and other technologies to capture this information. Your Smart TV transfers video snippets or TV tuner information in order to determine the programs watched.”

I don’t have any firsthand knowledge of the methodology in use here, but this seems like the most likely, if not the only feasible, source.

(Related: https://news.ycombinator.com/item?id=21427405, https://twitter.com/simpleoptout/status/1191029269691957249)