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playlistIdparameter cannot be found." Domain: "youtube.playlistItem". Reason: "playlistNotFound". Location type: "parameter". Location: "playlistId".
Did you added your own Google API key? Look at the help.
Check in YouTube if the id PLWc1yfTYfqNFd_wwRFJnHsRKnn1C3oJlq belongs to a playlist. Check the FAQ of the plugin or send error messages to support.