Had the same issue. When I clicked on the Vudu icon there was a button at the bottom to get my $15.00 free movie credit. I clicked on that I was taken to an information/registration screen for Vudu. Once I completed that I was able to access FB. So you have to register with Vudu to access FB. I then received the following email:
Congratulations , your Vizio Blu-ray Player has been successfully activated. Welcome to VUDU, the world's premier high definition on-demand movie service!
We have provided you with an account credit of $15.00 to be used towards the rental or purchase of any movie on VUDU.*