If you stumbled across r5---sn-cvb7sn7r.googlevideo.com, you likely saw a 404 error page. That's because this isn't a website you're meant to visit. It's a backend server owned by Google, part of the network that delivers video content for YouTube and other Google services.
For a consumer asking "is r5---sn-cvb7sn7r.googlevideo.com safe?", the answer is straightforward: it's not a site you interact with, so there's no risk of being scammed or phished. The domain is hosted on Google's own infrastructure, uses a valid SSL certificate, and has no history of malware. There are no reviews to find because it's not a business — it's a piece of technical infrastructure.
The only thing you need to know is that this is not a fake or malicious site. It's a legitimate Google server that happens to be accessible if you know the address. You can safely ignore it.