Error type: "Bad Request". Error message: "Bad Request" Domain: "usageLimits". Reason: "keyInvalid".
Did you added your own Google API key? Look at the help
Check in YouTube if the id PLTZzbn-Y8XVVJHEgwpYdcpvnWMN1JgbBJ
belongs to a playlist. Check the FAQ
of the plugin or send error messages to support