If you came across rr3.sn-5ualdnzl.googlevideo.com, you might wonder if it's a legitimate site. The short answer is: it's not a site at all. This is a backend server used by Google's video infrastructure, and it's not designed for public browsing. When you try to access it, you get a 404 error and an invalid SSL certificate — the certificate doesn't match this specific address, which means your browser will warn you about the connection. That's a red flag for any normal website, but here it's just a sign that you're hitting a server that's not meant to serve web pages.
Because it's part of Google's network, the IP address is clean and there are no blacklist issues. But that doesn't make it safe to interact with — there's nothing to interact with. No contact information, no privacy policy, no about page. The site blocks all search engine crawlers and doesn't have any social media presence. For a consumer, there's no reason to trust or distrust this URL because it's not offering any service. The safest thing to do is ignore it. If you see this URL in a link or email, treat it like a broken or misdirected address — not a place to enter personal information or make purchases.