And in fact it is illegal for YouTube to lock your data within their service in that manner in the EU. You have a right to export your data and they have the responsibility to make it make possible to move that data to a competitor where technically feasible. And it clearly is technically feasible.
There’s a lot of talking past each other going on in this thread. Nobody is defending the RIAA or DMCA. But they exist and this outcome seems painfully obvious.
RIAA being mean, DMCA being bad and copyright being outdated doesn’t matter here. What matters in that the law exists and YouTube-dl made it really easy for the RIAA to make a compelling case against them.
Google isn't making that case because Youtube is YOUtube. The whole point is that it's a platform for family videos, amateurs, and all sorts of other things.
If the RIAA didn't want their content Youtube-dl'able, they should have used one of their locked-down platforms. They went to Youtube because the locked-down corporate platforms don't have the eyeballs. Now, they're trying to convert Youtube into one of those platforms.
My expectation is the RIAA will prevail, but because of deeper pockets and the potential for a multi-million dollar legal battle, not because they're on solid legal ground.