Hello, firstly, thank you for this script.
Suppose I have 2-3 accounts logged in to youtube web, will I need to change API key every time I switch account?

And which API shall I choose during credentials creation, User Data or Public Data?

This script uses an API-Key, so it won't have access to user data. I didn't even remember Google asking the question for user or public data when I created one years ago.

Of course the script won't be able to show the upload datetime if the video is private.