The study delved into the effect of instructional video materials vs. authentic video materials on vocabulary learning of extrovert and introvert Iranian EFL learners. To this end, Nelson proficiency test was administered to one hundred eighty (n = 180) language learners. Considering 1 standard deviation above and below the mean score, one hundred twenty-three (n = 123) language learners were selected for the study. These participants were distributed into 4 experimental groups (with 25 learners) and a control group (with 23 learners). Researcher-made vocabulary pretest and posttest which were designed using the vocabularies from the movies were also administered to the participants. The findings of the study after three weeks of treatment revealed that both authentic video materials and instructional video materials can have positive effect on vocabulary learning of Iranian EFL learners. This effect, however, is not different among extrovert learners. It was also revealed that introvert EFL learners benefit more from authentic video materials. The findings of the study could be used by material developers or language teachers who may wish to use video materials in their classes.