Hi Dennis,
It's not only eyeballed. In the very beginning of the sequence you see how he marks the fretboard with that template he is tapping on with his hands. In the next seconds you can see the
triangular marks the template left on the edge of the fretboard, so each cut can be initiated at the exact position and has to be aligned with the mark on the other FB edge. The same template left pinhole marks for position the drill bit when drilling the holes for the fret markers.
I had to stop the video to see those marks.
That is pretty amazing technique but not unachievable for an average luthier, although most of us would do it a little bit slower...
