@Sara-S I steer clear of this myself. I've yet to see a quilt finished this way that wasn't terribly out of alignment and sloppy looking . I have a queen sized log cabin that was won at a farm show after OH put my name in the barrel that is finished this way. It really is pretty awful, very uneven and probably a poly cotton to boot. My first quilt in class was a little flip and sew baby quilt that we were supposed to finish this way. They were dreadful. I'm slow, last one done, used a regular mitered binding.
It's easier to get a good, even binding put on then one of these put on evenly. Did you notice how crooked even her small quilt is? It wasn't squared up properly to begin with. Then at this scale even the quilting distorted the quilt top. You can't go back and true up the sides. Then she wobbled and cut the binding portion from 3/4" to 1". Do not finish the corners the way she did, too much bulk.
If you try this on a bigger quilt it just magnifies the problems. It would work on this scale, basically works as you put it, if one was very careful with their measurements and techniques.
When you say you would use a larger border then what they used, are you referring to the binding "flap"? I think her size was good for what she did. One inch, then folded approximately in half giving 1/2" to fold over the edge for the binding, leaving about 3/8" on the top as the binding. This is a generous binding width, pretty typical for regular large sized quilts. If I was trying this at home on this scale I'd likely cut to 1" and fold one side. If it seemed too wide I'd likely trim to 3/4". I suspect that would be a pleasing width on a small quilt.
Of course the "quilt police" don't actually exist. So you get to finish off your quilts how ever it pleases you.