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.
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.