From how it was described, I think it happens when you don’t watch something on their channel for a long time, either by the creator not uploading new stuff or the viewer not keeping up.
The problem was noticed by people trying to follow users like OnlyUseMeBlade who is unstable and has only been posting once every six months or so, but there is still a lot of interest about his potential return.
It says right above that box that it requires the WHOOGLE_CONFIG_PREFERENCES_KEY or that option will be ignored. My guess is that you have to manually edit some config file to turn that key on, or generate an encryption key yourself that you provide through editing a config and adding it to that line.
Edit: you probably need to add your own domain or IP as the root URL too.