Error type: "Service Unavailable". Error message: "The service is currently unavailable." Domain: "youtube.CoreErrorDomain". Reason: "SERVICE_UNAVAILABLE".

Did you added your own Google API key? Look at the help.

Check in YouTube if the id PLCQqKNbsPFS6KoCczEaiSwIHatfLhWKJs belongs to a playlist. Check the FAQ of the plugin or send error messages to support.