Split grade, as I learned and practice it, involves working with the high grade exposure first, finding an exposure that brings the shadows to the brink of the desired black, then filling in the highlights and "completing" the shadows with a suitable low grade exposure. What he's doing seems like extra steps. I must be missing something.
I always do the low filter exposure first. Works very well for me, as I'm more interested in the mid-tones and highlights than the shadows.
His technique is interesting, since his Grade 5 exposure doesn't account for the paper sensitivity issue at Grade 4 and above. But as long as the prints look good, it doesn't really matter.
My personal approach is to do a low grade exposure with a filter between Grade 0 and Grade 3, depending on the negative. I dial in the highlights where they have nice tone that is just a hair light. Then I go to the Grade 5 filter and work on shadows, and also to give the highlights a blast to complete them, sometimes quite generously to really make them come alive.
What I like about split grade printing is that we get the opportunity to work on different aspects of the print separately. Then when it's all combined into the final print I like how the whole becomes better, if we do our job well.