The vast majority of computer science lectures from 20 years ago are still relevant. A ton has changed in terms of frameworks but the fundamentals are mostly the same.
It's amazing how some people are familiar with every framework of the month and don't understand how a computer works...
[1] https://en.wikipedia.org/wiki/List_of_important_publications...
I did not mean my comment to say that seminal works in CS theory are useless, just that most of the books published in this field cover more practical matters and they tend to age very quickly. Like I have an e-bookshelf full of Packt freebies back when they did that, and those books aren't really that useful now unless I want to start on an old version of something.