Sentence:  ... after which the inertia of the camera causes the motor to <WSD>hunt</WSD> with fluctuating speed. 
Meaning of the word marked with <WSD> tags:  To be in a state of instability of movement or forced oscillation, as a governor which has a large movement of the balls for small change of load, an arc-lamp clutch mechanism which moves rapidly up and down with variations of current, etc.; also, to seesaw, as a pair of alternators working in parallel.