Regarding my question:
To summarize, I think it was a erroneous migration. I flagged it to try to get it back and it was marked as helpful, but no action taken.
I don't believe the migration was warranted. This is not a question about using Youtube, the webapp, this is about using a command line utility yt-dlp that downloads content from Youtube. Webapps doesn't even have that tag around while SuperUser does. It already has a home here.
I have an answer to the question and full explanation why my tests were failing, but I can't post it (and considering the question is already off-topic at the migrated-to site, I don't want to post there).
Can this be undone?