The original post said, "(YouTube is) a store of culture almost. A wealth of information and video would be lost, like rare videos which are only on youtube."
Archiving a store of culture and almost infinite rare videos is definitely not a straightforward and easy solution. Yes, you can save few interesting videos locally. But, that's not the point of the original post.
a completely straightforward and easy solution to the problem
But it isn't, due to the lack of coordination or standards. That's why protocols get established in the first place; without them, valuable stuff tends to get lost.
If you don't want a solution and just want to talk about it that's fine. But his comment was productive and useful.
I use youtube-dl almost daily to archive interesting videos locally.