I was going to say that digging through wan shows to find a reference was too hard but then duckduckgo gave me a hit of a HN post I made that referenced the twitter post.
https://twitter.com/linustech/status/1008752236027973632?lan...
And here is the wan show discussing it (thanks to a comment on HN): https://www.youtube.com/watch?v=SKtJY6soCds&t=698s
I'm guessing that either there's some clause in the YouTube partner/adsense program saying you can't just redirect your viewers elsewhere or you can't upload videos with the sole purpose of saying "go here for more videos".
That said, I'd be interested to see the details of what GP was talking about, because I believe it exists, I just wonder what the exacts are.
[0] https://youtu.be/oOOOfZWXPu4