My process is for fixing up a file that was created and saved with units as px, with an “assumed” number of px per inch. Or for manually creating an svg from scratch. I have seen other processes to calculate and modify the height and width values to get to the same place. Using different tools. The preferred way is to tell the editor (Inkscape, Illustrator, etc) what the units are to start with, and let it deal with them from then on. My notes belong in a reference someplace, on how to fix things up after they went wrong. Which is probably not part of your videos, except as a reference to the forum here and wiki.
My process for scaling is actually very simple … if you are used to working with plain text files (not just word processor documents). It is a matter of setting 2 values, with the unit string added to the end, based on 2 other numbers. All of which are in the first few lines of of the svg file. Removing the px units from the rest of the file is separate, and can be done many ways, using many tools. A search and replace with a text editor is one way, and again is simple, if you are used to that sort of tool. Well, that and understand that an svg image is a normal text file, that is nothing like a jpeg, or other bitmap format.