YouTube Watchpoints

YouTube is not part of Google's core applications, and so videos you've uploaded to YouTube do not count towards your total account storage.

However, there is no supported way to transfer individual YouTube videos to another account, UNLESS you have created a Brand Channel and the videos live in the Brand Channel.

https://support.google.com/accounts/answer/7311601

You can download your Youtube videos NOT in a Brand Channel by using Google Takeout.