In Australia, the only cheese you could buy in the supermarket in the 1970s was Kraft in the little blue packets sold in the dry goods section.
To buy “real” cheese you had to go to a dairy, or go to the city centre and buy cheese cut off the block and wrapped in greaseproof paper from a contintental delicatessan.
Polyethylene film was not available.
So when it came out and you could buy real cheese in film from the supermarket, Kraft responded by bringing out "more convenient " Kraft Singles, which you didn’t have to laboriously (?) cut from the block.
When you upload a song, you indicate whether it has copyright and who owns it, Then, whenever its played they pay the copyright owner based on an audience size basis, similar to Spotify.
If you don’t, the copyright owner informs Google, and they close that link.
Even if you have music playing in the background of an instructional video, the copyright holders will go after you.