They are very useful as reference sources for many building with LEGO Technic. It looks like they are a result from very singular way of living the LEGO passion and stay in life.
Now you may find a lot more creations and recent videos, from his LEGOstudio website, which he divided into: Main Works, Small Works and Joke Works.
Below just a few amazing and brilliant produced videos, well representative of Isogawa's genius that I've selected to highlight here today.
These and much more, found at ISOGAWA Yoshihito's Channel at YT.
You may also find a lot more about Isogawa's work, from his work, books and one article at BrickJournal 8 Vol. 2.