I watched this video three times. The first time I thought of them as shapes, and trying to assign emotions and motives to them.
I saw the big rectangle as big-triangle's territory.
I saw the big triangle as annoyed and didn't want anything to do with the other shapes.
I saw the circle as being something big-triangle wanted
I saw the triangle get really P-O'd because circle ran away with little-triangle.
Second time I watched it, I saw more details, and I could ascribe actual human roles to these shapes.
I saw big-triangle as a man, little-triangle as some passerby-dude, and the circle to be some chick.
The man wanted the chick and pushed the little dude out so he can have the chick.
The chick didn't want anything to do with the man, and ran away with the little dude.
Third time, I could see the big triangle is the father, little-triangle the mother, and the circle a kid.
The kid watches the father beat up the mother and hides in the house (peeking around the door to see his mom, until she hides behind the wall). The kid retreats into the far corner of the house, scared.
The father comes in, and the kid tries to run away. The mother rescues the kid by opening the door, and they go off together.