Error type: "Forbidden". Error message: "The referrer null does not match does not match the referrer restrictions configured on your API key. Please use the API Console to update your key restrictions." Domain: "usageLimits". Reason: "ipRefererBlocked".
Did you added your own Google API key? Look at the help
Check in YouTube if the id PLEDB635CF2959F3FF
belongs to a playlist. Check the FAQ
of the plugin or send error messages to support