>>574
youtube-dl --username *****@gmail.com --password ***** https://www.youtube.com/watch?v=***********

Authentication Options:
-u, --username USERNAME Login with this account ID
-p, --password PASSWORD Account password. If this option is left out, youtube-dl will ask interactively.
-2, --twofactor TWOFACTOR Two-factor authentication code

TWOFACTORは二段階認証