Problem: What are the most important words?
time lapse of sun rising behind clouds with fog covering city like a blanket
Answer: city, cloud, lapse, sun

Problem: What are the most important words?
close up of a doctor with a stethoscope around his neck
Answer: close, doctor, neck, stethoscope

Problem: What are the most important words?
a field of wheat ready to ripen for harvest
Answer:
field, harvest, ripen, wheat