With the new rules and API version 3 changes YouTube is requiring all users that want to view videos outside of YouTubes website to register and create a Project to access the API. The good news is this process is fairly simple.
In order for you to get the YouTube feed working you need an API Key. Here is the process to obtain that.
VERY IMPORTANT: If you get an error notice the best thing to do we have found in the trials here is to absolutely delete the Public API access. Then add it again.