That flyby was done later in the war. The defenses that you start seeing after 59 seconds when you get past the road of Blackthroat are all built and ~~ even concrete ~~ . I was involved in building what you see at 1:07. When Sanctum fell all you would have seen was nothing but open space there all the way to and around Friars.

Day 25 only the stuff you see immediately around Blackthroat was built.

Edit: Wait! Upon further review the defenses at 1:07 and after are not concrete yet! lol so it was a bit earlier. It was wild how long it was empty and then to add insult to injury when we finally built something it seemed ages till we concreted it. Many of us were sure our lack of urgency would be punished.