Login to YouTube Without Accessing Gmail Using Same Account

Google has enabled multiple sign-in with the use of Switch Account. YouTube also supports this ability to switch between accounts.

For Gmail

1. Login to Gmail
2. Click your full name or email address in the Google bar.
3. From the dropdown menu, click Switch account or Sign in to another account...

For YouTube

1. Click your username in the upper right hand side of the page
2. From the dropdown menu, above sign out, click Switch account.

Once you're logged in to both accounts, you'll be able to go back and forth between them without having to log out and log back in with different accounts.

See additionalemail@gmail.com is an alias for realemail@gmail.com, which implies that addtionalemail@gmail.com is something like: real.e.mail@gmail.com re.alemail@gmail.com or realemail+anything@gmail.com

This is not a separate GMail account and so you cannot receive separate emails for this. You do not have a separate inbox for this. You can create a filter so that the emails sent to the additionalemail go to a particular label.

You can try creating accounts on different sites using additionalemail, you try to subscribe to something using this additional email.

If you go to GMail>Settings>Accounts and Imports you can add additionalemail under the Send Mail as and send e-mails as additionalemail (but the complete header of the sent email would reveal your realemail@gmail.com).