I used to think BW pathfinding was pretty bad too...eventually they will reach their location with enough spamming of mouseclicks
until i tried WC2 recently. that was the shit. depending on the terrain units get stuck in random cliff/tree spots and you have to manually guide them out of the mazes
That marine block at beginning of the video makes me think... I wonder if the animator is knowledgeable enough to use Jaedong constipation ramp as a homage.