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Thanks for the clarification. This confirms my assumptions.
I don't have time for a 10 minutes video (what happened to just writing text?), can you give a summary?
Not a summary, but my own opinion: partially leaked seeds are vulnerable for brute forcing at some point in time. Shamir's secret sharing can be used instead.
You're basically turning a 1-of-2 multisig into something where you need 2-of-3 locations to recover the funds. Why not use a 2-of-3 multisig the way it's intended, and add all public keys to each share?
That's a good question. A difference is that with 1-of-2 you don't need to deal with partially signed transactions, which might be a convenience with less experienced bitcoiners (like my heirs).