This is not me or my video, I found this on Runners World but explains it way better than I did.
You are all right that it tightens the shoe around the ankle but I think what it meant for me was that my whole foot was a bit loose in the shoe and lacing up this way just secured it enough to stop the rubbing on the side.
Runners World Race Lacing Video HERE
.... and if anyone can get this knot right PLEAZE let me know ... I just CANNOT do it!
The Ian Knot
Happy running & exercising.