If you try to log in with Facebook and get an "email required" error saying "We could not log you in through Facebook because PBS was not provided access to your email address," and you want to use your Facebook account as your activation login,
1. Go to https://www.facebook.com/settings/?tab=applications
2. Click on the "PBS Video Portal" app
3. Make sure that in the "Info you provide to this app" that "Email address" is checked.