i had a problems to upload my files direct from hitfilm to youtube. There was a hitfilm-error-message like "The login request used a username or password that is not recognized."
I was confused an tried all possible usernames an passwords. Nothing helped.
Google send me mails like "Login attak blocked" (my translation).
After a while i found that hotfilm is a "less secure application". I had to enable less secure apps in my google account (https://www.google.com/settings/security/lesssecureapps) and the Hitfilm-Youtube upload works like designed.
Hope it helps.
Greetings from Germany