If the Internals die, you just replace the blade and send the old one back.

The motherboard in the video appears to be a Supermicro Twin 1u.

It looks like a blade, not a 1u.

I'd estimate its going to be just over a 1000KG for a full cabinet.

The coolant is contained within sealed processing node cartridges, with seporate hard disks, so no you won't have to see this.