Metaprogramming tutorial on YouTube

Stream: lean4

[Tom]

There is an series of videos on YouTube (https://www.youtube.com/playlist?list=PLlF-CfQhukNnq2kDCw2P_vI5AfXN7egP2) called "Metaprogramming in Lean tutorial". Given they are from 2020, I assume they don't focus on Lean 4.
Is anyone here familiar with them and could tell me how much of the material is still relevant in Lean 4, so I can spend my time wisely?
Thanks!