Wow, great stuff! He definitely emphasizes going right for the opponent without needlessly blocking sword-to-sword (if possible), and I think this is very important.
The similarities to iaido are stunning. I knew that gumdo derived from kendo/kenjutsu, but this is virtually indistinguishable from it. Or is he teaching kendo, as per the URL?
The instructor claims membership in the Korea Kumdo Association, the Korean affiliate of the International Kendo Federation. So, he is probably effectively teaching some form of Iaido - The Siljun Dobup he claims to teach apparently translates as 'Real Combat Blade Methods'.
As for the similarity to Haidong's Ill Soo Sik Deh Ryun, well, there's only so many ways to use a two handed saber, and our founders had to start somewhere.
This complete video is now available in English, and it provides a great introduction to the etiquette and the art of the sword. You can see this and other parts of it, as well as information on kendo/kumdo and siljun dobop, at the school's website here.
GREAT video for any sword enthusiast's collection.