@SamPatt Good post, including the clip of grandma's anecdote.
It would be a good idea to add a final step of burning the videos to M-disc. SSDs and spinning platter drives aren't reliable for long-term storage. You could use a tape drive if the file sizes are too large, but M-disc lasts longer and doesn't require pro hardware to read.
I use M-disc and I am sure the discs will stay safe for a long time. What I worry about are the drives! It seems the business of making drives is not profitable. So companies exit or reduce.
I assume the backup is the copy in R2.
That's better than nothing. Personally, I wouldn't consider it archival storage, so much as the possibility that 20 years from now Cloudflare (or a holding company) pays me $100 compensation for my lost data!
Just fyi, you can just use BDXL discs(get them while you still can!) they use technology identical to M-Discs and should last just as long.