YouTube is now requiring you to log in with your Google account. Here's what you need to do.
1. Log into Tube Toolbox with your Google/Gmail account and password
2. Log out of TubeToolbox
3. Use this link to switch your Professional account from your old account user name to your Google account user name -
http://www.tubetoolbox.com/accountswitch.aspx4. Log back into Tube Toolbox with your Google/Gmail user name
5. You can click on Manage Account under Data to copy your messages,lists & history from your old account to your new Professional account – This can take a LONG time to complete if you have lots of data. DO NOT CANCEL DURING THIS PROCESS!