What's actually wrong with this persons activity here though - they're [presumably] new and haven't had chance to learn all about HN yet. Their questions/comments don't seem so terrible that they should be hellbanned, or do you disagree.
Presumably what you're saying here is that no-one should have the chance to warn those who're hellbanned, we should trust the secret machination of HN to always be right?
I actually very often disagree with the secret machinations of HN.
It's not that I agree or disagree with this particular banning, but that in the aggregate, "you are a new account and you post a link to youtube" is a pretty good general characteristic. While it's unfortunate that there's sometimes a false positive, most things that I see explicitly dead deserve to be.
Besides, it's pretty easy to figure out if you've been hellbanned, and then if you're real, you can ask dang (I guess, now, eh?) to reverse it. No warnings needed.
(and yes, I agree, it'd work even better without showdead.)