When I search on 'recover old youtube account' or something similar, I get these suggestions:
- Navigate to the YouTube homepage.
- Click the “Sign In” button in the top right corner.
- If you haven’t logged into your account recently, click on the “Need help signing in?” link.
- Enter your username, email address, or phone number.
- Receive a verification code in your email or via text.
- Enter the code to reset your password.
- Sign in with your new password.
Looking at the current sign in procedure, the 'need help' bit appears to be missing, but there is a 'forgot e-mail' option. You can use that to recover the e-mail that's linked to that account, but only if you originally supplied another e-mail address or phone number for recovery purposes. If your videos are still online, they should be linked to some sort of account that used to be in your name. The page with the video(s) on it should allow you to see which username you used. If you know which e-mail is linked to the account, and you have access to it, you should be able to go through the 'forgot password' procedure and set a new password for the account. There is no rule that says you have to use a Gmail account, I have a youtube account linked to a totally different e-mail account, works just fine.