A couple of comments on this...
These fans do not like either PWM or 19V...
There is almost no difference between 80 and 255, and even at 6/7 they are already fast.
The other thing is the Error, and it is most probably caused by the PWM noise on the line. That should be solved if you use the 'Slow PWM' option of the builder.
My recommendation would be -- in that exact order:
1. Build and install a 'Slow PWM' firmware, all other fan option set to default -- use the Experimental branch as we need one of the features there.
2. Test the firmware to see if you get error while printing. I yes, don't go further, we first need to solve that.
3. Find the lowest value your fans are still running once started. It is important as your fans are going hard at low PWM, we want to use the full range.
So you go to let's say 10 to get them running -- you might expect different values from your tests in the video, since 'Slow PWM' is now enabled -- and then go down one by one until they stop.
If they are still running with '1', then go to 4a, otherwhise do 4b
4a. Re-build a firmware with 'Slow PWM' and kickstart (300ms should be enough)
go to 5
4b. Re-build a firmware with 'Slow PWM', kickstart and 'Fan Minimum PWM' set to the lowest value your fans were running.
It will probably be '5' -- This is currently the lowest granularity in the builder (I could increase granularity)
For kickstart 300ms should be enough
go to 5
5. Make a test, your fans should start now at 1 and continue to spin
If they don't start, go back to 4 and increase kickstart delay
If they start but stop after a while, goto 4b and increase 'Fan Minimum PWM'
6. In Cura (Advanced properties in Cura Legacy), set the Max Fan to reflect the maximum speed we want. I might be different with the 'slow PWM', but based on the video, it does not look to me that we get much more flow beyond 80, so I would set the Max in Cura to about 30%)
That way we should be able to use the best range for your fans.