I've yet seen another game with as good pathfinding as StarCraft 2. The way 100s of units flow around another 100s of moving units like water is very impressive, even today.
> whenever harvesters are on their way to get minerals, or when they’re on the way back carrying those minerals, they ignore collisions with other units
Maybe that's part of the fluid behaviour you noticed.
The blog contains more technical posts about StarCraft 2, so you might find that "special sauce" somewhere else in there :)
The blog is interesting, but it is about sc1. Pathfinding in sc1 is so terrible that moving units where you want is part of what's make one a pro player.
Does anyone know what's the special sauce?