Is anyone still able to get this solution to work:
I have just tried to create a YT account using a Yahoo email address and you simply cannot get past the box that requires a Google accounts user name which it then turns in to a gmail address.
I made up a name (as I already have a Google account) and then inserted the Yahoo email address where it asked for current email.
Once it created my new YT account I then got out of that back to the YT login screen - on my PC. At this point I inserted the yahoo email address and password but it said it was not valid. So this confirmed it has just created another Google account.
I tried to use this new Google account to login to YT on both the WDTV Live and my iPhone and still get the invalid un and p/w message.
I am convinced this is a Google issue (not WD ) as the same problem occurs using the YT app on an iPhone (yet you can login to your account on the iPhone if you go through the browser).