The parameter changes that are made in the second example are as follows:
The style of the nodes is changed so that (a) we use a standard text font and (b) the node is shifted down relative to the horizontal lines
The standard lengths of dirtree are adjusted, so that (a) the dots at the cross are the same wdith 0.4pt as the lines, this is the last two parameters and (b) the vertical lines are moved further under the nodes, the first parameter 1em. The second and third parameters have their standard value
The internal baseline skip of dirtree is made larger, moving the lines apart and moving the tops of the vertial lines down, so they don't cover the shifted text.