It's difficult to see in the video, but I've downloaded it and tried it, and on a real screen, it's very obvious that the grid is made up of cells that contain two letters, like [MK].

I'm not sure if I had a use for this, but it was extremely easy to use. I'm already looking where I want to click anyway, so when I hit the Command key, two letters appear where I'm looking, I'm typing them and space, and I've clicked the area.