Anti piracy “watermarks” on you tube videos?

I like to cruise you tube after some cold ones. I’m talking about beer. Yeah, I said it. Ok., I have noticed on some of the older stuff, 60’s live performances, that the background seems ro swirl about with the foreground figures remaining pretty steady. I know that’s not what the source looks like because there are other versions to compare to. My question is, why and how do they do this?

 

Can you post an example?

 

Yes. This French TV broadcast of T. Rec at the 30.00 minute mark and onwards. I know the source doesnt look loke this.

 

I don't know if this applies to what you are describing, but I've seen other videos altered and assumed it was to prevent them from being auto-detected as unauthorized. One example is full episodes of the TV series Golden Girls -- weird cropping, soundtrack pitch altered. It's pretty easy for a "bot" to detect a source when it isn't significantly altered.