I own the SP3, and that video is accurate.
But I disagree that the SP3 works well on lap in laptop "mode." The keyboard is so close to the crotch that he can barely get his hands in to type, and it doesn't seem workable medium to long term, I have exactly the same experience.
I never use the SP3 on my legs with the keyboard cover, only as a tablet + on-screen keyboard. However the keyboard cover works great on a bed, tablet top, or even floor.
PS - The Windows on-screen keyboard is garbage. Still no swipe/gesture-entry support even all these years later. It is as bad as Apple's default keyboard (REALLY bad).