If you haven’t visited Michael Hopkins’ String Pedagogy Notebook, you need to go check it out. It is a great site that helped me a lot when I first started teaching strings. I contacted him and he even allowed me to use it as my textbook when I taught the string techniques class at the University of Houston.
So, it seems that Michael Hopkins has taken down most of the content on his site as he will be creating a book along with complementary video content. You can view his video content on his YouTube channel here https://www.youtube.com/user/stringtechnique.