You’ve been fooled by film editors again. They used “interesting” footage of the robot (ie, footage in which it’s moving) and intercut that with footage taken by the robot when it’s not moving.
Just like the rock the otter was using to break open the shellfish changed from bigger than its head to something much smaller halfway through the smashing food with a rock sequence.
ETA: step one, put the robot in the water near some otters that are near the shore/your boat and film hero footage of the robot with a telephoto lens. Step two, pilot the robot out to visit otters much further away where your telephoto lens can’t deliver the goods and get up close and personal footage using the robot. Step three, edit the two sequences together in post production.
