I'm going to have to read that again, I found it a little hard to follow. Enjoyed it, though, as well as the related articles at the bottom.
Footwork is difficult enough in it's various milieus (boxing as opposed to whatever form of Karate fighting you do, or MMA or whatever) but writing about it is a chore, even with good graphics and video examples. I liken it to writing about position in Jiu-jitsu, or Kata in Karate, or batting in baseball. There's just so much to discuss and it doesn't always work on paper.
Also - the examples are sport orientated, which is fine, but boxing is a broad sport with a lot of levels and weight divisions, there's lots of differences in the lower weights compared to the higher weights.
Recently, the last month or so, there was a thread about where you look when you spar, or maybe when you fight. I always watch the feet. To me, it's like reading a menu.