Video prompt: Lava flows steadily down the slopes of a volcano, its molten surface rolling sluggishly over the rocky terrain, forming glowing rivulets and sizzling on contact with cooler earth.
Defect: Deformation (when Object is involved in an act,  anything in this process that's weird. e.g. people walk into a wall. "Walk" is an act)
Explanation: the rate in which lava flows is uncharacteristically fast. Lava generally has extremely slow movement.