It is clear that they are testing the minimum height you can drop someone from a parachute in the same way that the excuse of scientific knowledge of the moon was used for recording Soviet Russia signals through moon reflection.

They don't show you the cuts under the minimum height, but in the video you see a shoot of the chute almost not having enough time to open.

Dropping people at this height means time in the air is minimum and radar does not detect the plane, but is incredibly dangerous.