Alternatively to what was instructed in the tutorial, you can also use insets to create the same results much faster.
By selecting the three face of the ramp (top, slope, and bottom), you can create an inset that will automatically create the shape you want for the railings. Just extrude the necessary faces upwards, and merge the trapezoid face from the top of the steps with the bottom of the pyramid’s head with snapping. This will straighten up the railings at the top of the steps, creating a nice, clean railing in just a few actions. Just be sure to remove any doubles once it’s complete, because there will be some sneaky vertices in there.
Hope this helps!