The first comment underneath the first video is by Simeon Pilgrim from nikonhacker.com who asks some pertinent (and unanswered) questions about how this is done.
If you follow the trail back to nickonhacker.com you would imagine that, despite there not being a huge amount of activity on there in recent times, that something as significant as this would be generating a huge amount of discussion amongst the Nikon hacking community during the past two years since the video was published.
But there really isn't.
Which is pretty unusual really.
However, in the description for the first video, it states that :
"From our study, it can be done by yourself , as long as you have the right password file installed in XQD card"
Now the upgrade process for ProResRAW on the Z6/Z7 was purely software, evidenced by certain Nikon service centres doing a sub one hour while you wait service to activate it if you took it there personally.
Going back to nickonhacker.com, the very last post in the Z6/Z7 thread is this one :
This tallies with the description of the video that said "as long as you have the right password file installed in XQD card"
It is this key that will have been generated at the service centre and it will be based on the serial number of the camera so is unique and not transferrable to another camera.
And it is worth noting that the title of the video is "DIY enable RAW...." rather than "DIY add RAW".
So, based on all of this, what you are seeing in those videos is a camera that already has the license having the functionality disabled and then re-enabled through PTP.
In that sense, the "DIY enable RAW...." title is technically correct if obviously a little misleading.
What would be needed to make this work from scratch is the way to generate the "HDMIRAW.KEY" file which, after a two year gap, either doesn't look like its been achieved or, if it has, then it is happening in private with someone potentially profiting from it.