Basically, someone made something wrong and changed the configuration to access the database. The web server is trying to "talk" to the database (access to the website and all it's tables like users, videos, pages..) but the database isn't being found or responding. That usually means their connection to the database is misconfigured. If they changed the password to access the database for example, then that's all it takes to glitch access to everything else.
So yeah — the backend can't access the database, so the site can't load content properly. They probably just need to restart MySQL or fix the socket/host settings. Nothing major, but it’ll stay broken until someone with server access handles it.
I don't think that will be that soon, considering the website has been abandoned in all versions, including the italian. 
They did promise they would update the website to the reboot, that much is confirmed. But I would lower my expectations, I'm not sure much will remain in the website, look at all their new websites. Mermaid Magic has nothing... if they follow that trend...
