Not entirely sure what everything in this means, exactly, but it sounds relevant.
http://apiblog.youtube.com/search/label/clientlogin
-Jeff Posnick, YouTube API Team said:
Thursday, November 4, 2010
Update to the ClientLogin URL
We want to let the developer community know about a change to the officially supported URL for YouTube API ClientLogin requests. Previously, developers who wanted to obtain authentication credentials via a username and password had to send their ClientLogin request to https://www.google.com/youtube/accounts/ClientLogin. The new URL that we encourage all developers to use is https://www.google.com/accounts/ClientLogin. This new URL has been functional for a while, and is the same URL that other Google APIs use for ClientLogin requests. Switching YouTube API ClientLogin traffic to the standard URL ensures that developers across all of Google’s APIs will see standard behavior when logging users in.
All of the details regarding this switch as well as best practices for performing ClientLogin requests can be found in our YouTube API documentation. There is one specific change in behavior that is worth calling out: responses from the new ClientLogin URL will not include the YouTube username of the authenticated user, which the old URL’s responses did provide. We encourage developers to take advantage of the username default when constructing YouTube API request URLs, which always refers to the currently logged in user.
We have no immediate plans to disable the old ClientLogin URL, but we do encourage developers to update their code at their earliest convenience to point to the new URL. We will post again with further details if and when the legacy URL is turned off.
Cheers,
-Jeff Posnick, YouTube API Team
http://www.google.com/support/accounts/bin/answer.py?answer=165556
YouTube said:
Accounts › Help articles › Phasing out classic YouTube password support for users linked to a Google Account
Google Accounts: Phasing out classic YouTube password support for users linked to a Google Account
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Now users who joined their YouTube and Google Accounts together can only sign in to YouTube by using:
- YouTube username + Google Account password
- OR Google Account username / email + Google account password
You can no longer sign in with your YouTube username + your original YouTube password.
If when you sign in to your YouTube account, you receive messaging prompting you to use your Google Account password, it means that you have a linked YouTube - Google Account.
All you need to do in order to sign into YouTube is to use either of the two sign-in username/password combinations described above. Your YouTube username is not changing.
I’m linked to the wrong Google Account and want to link to a different Google Account
If you’ve accidentally linked to the wrong Google Account, here’s how you can unlink from the incorrect Google Account:
- Sign into your Account and go to your Account page
- Click “Manage Account” (on the left side of the page)
- Click “Unlink YouTube and Google Accounts”, and then the “Unlink my Accounts” button
- You’ll then see a green confirmation message letting you know you’ve successfully unlinked your YouTube Account from the Google Account
Once you’ve successfully unlinked your YouTube Account from the Google Account, you’ll be able to sign into your YouTube Account again using your YouTube username and old YouTube password.
After you’ve signed into your YouTube Account, you can link your YouTube Account to another preferred Google Account, by following the instructions listed here. Equally, we’ll start prompting you to link to a new Google Account each time you sign into your YouTube Account.
I’m linked to a Google Account that is not mine
If you’ve accidentally linked to a Google Account which is not your own, you should email the person who owns the Google Account (their email address will be the primary username of the Google Account).
Let them know you’ve accidentally linked your YouTube Account to their Google Account and you need their help in unlinking the two accounts.
Ask them to follow these directions and confirm with you once they’ve completed these steps:
- Sign in at http://www.youtube.com with their Google Account username and password
- Go to their Account page (http://www.youtube.com/account) and click “Manage Account”
- Click “Unlink YouTube and Google Accounts”, and then the “Unlink my Accounts” button
- They’ll see a green confirmation message letting them know they’ve successfully unlinked your YouTube Account from their Google Account
Once they’ve successfully unlinked your YouTube Account from their Google Account, you should then be able to sign into your YouTube Account again (using your YouTube username and old YouTube password).
More about Google Accounts
* To learn more about Google Accounts, please visit this page.
* Click here to reset the password on your Google Account. A password-reset link will be sent to the email address associated with your Google Account.
* Don't remember your Google Account username? Click here to find out your Google Account information.
Here’s why we’re changing the way you sign into your account:
* To reduce the number of passwords for your YouTube account.
* To make it easier to add more Google technologies to YouTube later on.</blockquote>