I see what you're saying, yadroc. Maybe this is an instance of "do as I say, not as I do". She also tells you to line your ruler up on the edge of the fabric for cutting on the bias -- which she does... then completely moves it before she starts her cut. lol
It's too bad an editor didn't notice those things. Everyone makes a little boo-boo sometimes. Now, what would really be helpful is if there was some tool that marked the X and seamed the two ends together for us. :P I think this is really more just for joining the 1/4" seam together to make the binding strip long enough to reach around the quilt. I can't imagine that part is giving anyone problems. It's that final joining together that is tricky. Up until my last little quilted changing pad, I always end up cheating it by running an overlap. No one ever noticed or complained.
For anyone interested, I found this great video from Missouri Star Quilt Co that gives a super clear, super easy tutorial for machine & hand quilt binders:
https://www.youtube.com/watch?v=0vCWpxBRs20