Great video, thanks for taking time to do it. It even has some of my favorite Ironhand quotes ("this is why we fly", "we do not shoot at..." etc.) :-)
I think that the HDD scale number has a somewhat different interpretation though. The number displayed is the length in kilometers of the line underneath it, just like on paper maps. This line should actually be 1cm long, so e.g. if it HDD scale is displayed as 10 then the scale is 1cm/10km = 1:1000000.
Now, it may be that the physical size of the display is 10cm from the own ship symbol to the top edge, in which case the two interpretations are really the same.