You can edit the special ellipse easily. Just (object) select it and you can change it's size freely with handles and move it around. It even has an option to move it along it's axis. Really handy. I actually only use this one instead of the single ellipse tool because of this adjustability. Maybe this movie was made with and older version where this was not possible but currently you can. No need to mess with the transform tool.
There is one already :) It's made by none other than the amazing Ben Marriott :) here's the link: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MG84WaG1xlE.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-YjgfuUxfgqU.html
I actually find clipstudio ellipse rulers to be astonishingly bad and useless. It doesn`t show the degree of the ellipse, it doesn`t show the minor axis of the ellipse to align it in perspective, so it pretty much has none of the needed functions any ellipse guide has and what you need for technical drawings. Lazy Nezumi is sadly the only answer to that.