Time to test out the cryptic binding tool.
Step 1: Marking each end of the binding:
And here's the result once those two diagonal edges are sewn to each other:
So the binding tool does work. The instructions are not the best. The tutorial on the website doesn't really help because it doesn't show clearly where the cuts should be made. But now that I've figured it out, I might just find this tool handy in future!
After I finished this one, I thought of another way the tool might work. But I will have to wait until I have another binding to apply to test that idea.