I wouldn't consider my DVD collection as particularly sensitive data that I'd be afraid of putting on my internet computer. And that would go for my modest collection of ripped audio and videos as well.
I.e. just keep your actually private/sensitive info on your offline computer and turn your internet computer into your audio-video premium device.
Ripping/saving a youtube video to watch on your offline system seems like a lot of work. How do you move the video? With a thumb drive or do you have a LAN so that your "offline" system is still on your local network? If the latter, then there are software solutions you might want to explore. E.g. turn your mostly "offline" system into a virtual a/v device that you can use from streaming on the internet computer. E.g. when we watch MS.Now via a free streaming service I configure a mac to stream from the net, but send the audio/video to the Apple TV device as a remote screen. Needed because there's no app on the Apple TV box to display video streams from https://usnewson.com/watch/msnbc-live). There are a lot of screen/audio sharing software solutions that you might find useful and would avoid the hassle of ripping and copying the videos.
Btw ... I'm likely as old as you. But I've been using the Arpanet/Internet since the early 70s and am quite aware of the security implications and how to keep my machines backed up and secure.
Humor: I also have a physical blueray DVD player hooked up to my TV. Once in a great while it actually gets used! Much more common is watching a streaming service or youtube over my Apple TV box. And Apple seems to be moderately decent with not snooping on my viewing habits. Better than google at least.
And yes, there's no safe internet computer. But what I consider to be private information is really pretty small compared to my a/v usage.
> Because if you lose your internet connection you're outta luck
Well yeah. But losing access to entertainment is hardly a crisis. But to be honest, I need the internet to get my work done, and my ISP's suck, so I actually pay two internet ISPs so we have redundant connectivity.
= new reply since forum marked as read