Can peertube-import-videos.js be used on others' servers?

It says « Scripts can be launched directly from a PeerTube server, or from a separate server, even a desktop PC. » Does that mean I can use a separate device to mirror a channel onto an existent peertube? PeerTube/ at develop · Chocobozzz/PeerTube · GitHub

Yes. As said in the documentation, the script takes following parameters:

--password 'PEERTUBE_PASSWORD' \

Videos will be imported on the computer where the script is called, then uploaded to the server.

Would you, by any chance, know how to set it up on Windows?

No sorry. I’m not using windows at all.