The speed at which traps close generally depends on health and temperature of the overall plant, so I'm told. This action happens once one of the small trigger hairs is touched twice in a row by an insect. (This is why dead bugs don't get eaten without repeated triggering after closing, the trap thinks it "missed" and will re-open over the next day.)

Once closed, the video is sped up to show how the trap continues to seal as encouraged by the trapped insect.