I found a video about Gothic Arch modeling on Youtube using Blender 2.78.
At 1:28 the creator extrudes the vertices of the arch.
However, I can't figure out how it was done. The keydisplay does not show any special shortcuts. The extrude settings on the left seems to be default.
How to reproduce this extruding behaviour? Any shortcuts or settings changes? Additional plugins?
I guess some shortcut since there is that small (black) gizmo with the dottet line.