Right, but you don't train a model by pointing a camera at a screen. You download the video file. You deliberately bypass the copy protection. I'm not saying it should be illegal, I'm saying it is.
I'm not sure about literally downloading YouTube videos, you might be right about that.
At least under US law, the person downloading the images has to be the same one who trains the model, because giving them to another person is copyright-violating distribution.
To be clear, I'm just sick of corporations being free and clear to do things that would get the rest of us stomped.