Error type: "Forbidden". Error message: "The request did not specify any referer. Please ensure that the client is sending referer or use the API Console to remove the referer restrictions." Domain: "usageLimits". Reason: "ipRefererBlocked".
Did you added your own Google API key? Look at the help.
Check in YouTube if the id youtube belongs to a username. Check the FAQ of the plugin or send error messages to support.