Downloading your favourite stuff is absolutely what you should do, but it doesn't solve the bigger problem.

Many from my generation, who grew up during an era of information scarcity, have huge stashes of hoarded data. But what can we do with it? There is no way to legally share it, so we take it with us in our graves.

EDIT: Many good comments, but they all suffer from one blind spot, so I answer here instead of individually.

A lot of content is only legal because it is on YouTube (or any other platform that has deals with the content industry). Sure, we can share illegally in a way that is obscure enough that no one gets sued. But what help is that, eventually it will get either popular and sued out of existence or forgotten and fade.

Then there is old content that is not legally shareable at all, like old game ROMs. Plenty of millennial stuff there but the Gen-X world is already half forgotten.

Cooyright is just too long and too unreliable. What we need at least is exemptions from Copyright for archivists, otherwise a lot of stuff will simply be lost in the coming decades.