On top of that, the drives might be somehow paired to the motherboard. And I would imagine that pairing a new one with the existing motherboard may require some proprietary software that only Apple has.
These are only my assumptions though. People e.g. at Louis Rossmann's repair shop might know more.
It is funny because the video is 50 minutes long which requires a difficult soldering job and chip reprogramming. This does not include the process of opening the Macbook Pro, disassembling it, removing the logic board, nor the reverse process.
If you throw enough money at a sufficiently skilled technician it can be done, but no M.2 slots in sight here.
I'm disappointed a mainstream laptop is soldered, though. Why would anyone buy it?