Very nice. It looks like hers is in the Moleskine "Japanese Album" with foldout pages, which I hadn't seen before.
I caught that, too, and also, that the last page has been cut loose from the binding. That probably was done so that the book wouldn't expand, since an appropriate number of panels can be removed at the end to compensate for the increasing thickness as materials are added. Also, once cut loose, the back sides of the panels, normally inaccessible, would be usable. Of course, to serve the end of managing the size, it might help to use the front and back of each panel before going on to the next, snipping out the necessary pages at the end each time. This could drive the reader nuts; maybe that's why she doesn't seem to have done that.
This video was very enjoyable, for me. I've kept sketchbooks over several decades now, very erratically, but frequently I've glued in whatever needed preservation for any reason, even to the point of packing a gluestick with me. M E M is a working artist, and she uses this format here not so much as a portfolio, but the way many artists do to keep notes, sketches and ideas in whatever form they might occur. It is very interesting and informative to see how she uses her book. I'm certainly going to explore the idea of using the Japanese folding book.
I went to Moleskine's site thinking that I had seen a version of their sketchbook, maybe the watercolor book, which had every page scored for potential removal. The site makes no mention of anything like that; only the extra small Volant notebook is said to have every page removable. The larger versions have only the last 16 pages scored as have the cahiers. That wouldn't work as well as being able to tear out the next page when necessary.