Just about to measure and mark up my neck.
The instructional video shows the fret0 line to be right on the join between the straight length of the neck and the angled peg head....
But that means the nut will be placed on the angled peg head and require a channel to be cut out to square it back up.
Wouldn't it be easier to crib a bit off the straight section (nut width) and place the nut on the flat and butting up to the fingerboard? (Avoiding having to cut a channel for the nut) and simply move the 14th fret mark further away?
Hope this makes sense

Cheers