I have also wondered about the possibility of media emitting some kind of hidden identifier. Can normal speakers emit noise outside of human hearing that could contain a unique id? Would not even need to be a lot of data that could be broadcast.
Streaming services watermark the video as opposed to the audio as I understand it.
But that's for tracing pirated content back to the originating user account. It's not particularly useful (also entirely unnecessary and overly complicated) if your goal is to ID a piece of content as opposed to an account.
That can't recognize what you say. But, it can ID where you are in a specific show out of zillions of hours of shows.
A quick search for “audio steganography” should answer your question (and be a fun rabbit hole if you find that sort of topic interesting)