Richard Stallman on «The Danger of Software Patents»

Error type: "Not Found". Error message: "The playlist identified with the requests playlistId parameter 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 PLRojJguHprGb-9-oZs_oPMHOfpcL2vbc6 belongs to a playlist. Check the FAQ of the plugin or send error messages to support.