I've always done my bindings this way, too. I think I lift the corner fold a little more than the tutorial, to make sure I don't catch it when I start sewing again, and that way I am pretty sure to have a square corner. I miter my ends, though, even when I make placemats, even though that is a little difficult because I don't have lots of room to work with. It makes the binding all sewn, all perfect.