There are various ways of making Longstitch bindings. The example above is a very basic and simple form - some have more complex - and more robust - ways of attaching the sections, so they are connected together more firmly. Many longstitch bindings are very decorative. It's possible to cross, plait or weave the threads, to make patterns, or to thread beads onto the binding as you stitch.
Some bookbinders I know make fabulous longstitch bound books, some with beautiful decorations.
Marie - Wee Bindery
Rhonda Miller - MyHandBoundBooks
Katie Gonzalez - LinenLaid&Felt
Beth - UberArt
I think this post is long enough; I will make another one - or two - about other bindings and post them soon! I hope that (so far) this has been an interesting and perhaps a bit useful tutorial.