Looks to me like a Rube-Goldberg way to avoid the Advanced Scene Switcher plugin. Yes, the video works, but you have settings all over the place to control what is logically a single operation, and each setting has a different way to get to it and a different way to maintain it if your needs should change. Good luck remembering all of that!
With Adv. SS, you can have everything all in one place, except for one, which is only to start OBS at all. No special options needed, just start it. Everything else is done in Adv. SS.
To "just start it", I would recommend using the old "Startup" folder. It seems to have disappeared from the user interface, but the functionality is still there. Open the start menu, right-click the OBS launcher like the video says, but stop when it opens the folder. Copy that shortcut, go up a folder, create a new folder called "Startup" (without quotes) if there isn't one already, and paste the shortcut in there. Now OBS will start with Windows.
As long as OBS is running, Adv. SS can do everything else, using the Macros.
If you want to use OBS for something else too, without messing up the automated one, then you can modify both shortcuts to use different options. obs --help
in the Command Prompt to see all that you can do there. Add the appropriate options to both shortcuts, so they don't run over each others' profiles and scene collections, don't complain about each other, and generally play nice, but no more than that. Again, all of the automation is in Adv. SS, and nowhere else. (Adv. SS's settings are in the scene collection, so that's already covered)