I was doing my best to follow this tutorial from the Blender Guru, but, alas, 8 minutes in I've run into a real spot, a few moments after this spot in the video.
I can only hide the selected, not hide all BUT the selected. (Edits then effects ONLY the selected vertices.) I know, there is a way to invert selection, but it doesn't look like he does this.
Also, what does he mean do he says, "This is not perfectly aligned..."