Nothing to see here. These performances are from 1984, which means that the recording companies that own their copyright have the right to block them in the US and other countries.
False claims are endemic for classical youtube uploads. AI systems and human agents alike conflate different recordings of the same work more as a rule than as an exception. Both ability and incentives create a massive bias in favor of this state of affairs.
I thought this was a reference to 1984, but nope. I checked the other videos on the channel, and it was indeed (professional) performances in recent decades, which has a separate copyright. In this case, as law stands now, UMG (Universal Music Group), with the agreement of the performer*, owns the rights of the performances.
* Whether the performer have regrets (seems unlikely though in this case) is for outside discussion.
