So... I looked at this and thought... uses a plugin which I won't have so there is not much I'm going to learn here. How wrong can you be
First thing I learned is there is such a thing as a guide point... not just a guide line. I paused the video to try it out. Think that one will be useful.
Then you copy a line, hit / for divide and enter a number and get multiple copies equally spaced over the copy distance. Guess I could have looked up how to do an array in sketchup but I might equally have just assumed it would be in the pro version as there is no icon for array.
Then came flip along. Something else I'd never done. If I wanted a copy to be reversed I've always used the scale tool and scaled it to -1 in the direction I needed. Flip looks easier.
Just when I thought that would be about it... I find out you can get back to the select tool at any time by hitting the spacebar!
It occurs to me that the plane view (not a solid) you had at around 5 minutes in could be copied along the axis and a solid created by drawing in the lines that would otherwise need a plugin to push pull off of the normal 90 deg.
Anyway, not a plugin I'll be buying/using but I learnt a lot by watching the video. Thanks Dave.