If you've come across rr17.sn-pmcg-bg0e.googlevideo.com and wondered whether it's safe, here's what you need to know. This address is not a typical website. It's a server hosted on YouTube's network, but it returns a 404 error and the SSL certificate is invalid for this subdomain. That means your browser will warn you that the connection isn't secure, and you won't be able to load any page.
In the world of infrastructure servers, a valid SSL certificate is the bare minimum for trust. This one doesn't have it. There's also no history in the Wayback Machine, no whois record for this subdomain, and no contact information. These gaps aren't unusual for a backend server, but they make this address unusable for anyone trying to access it normally.
The bottom line: rr17.sn-pmcg-bg0e.googlevideo.com isn't set up for public use. If you see this URL somewhere, it's likely a misconfiguration or a failed link. Don't rely on it for anything.