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.