This study investigates first whether news video in a computer-assisted language learning (CALL) program can foster second language (L2) comprehension and incidental acquisition of adjectives, nouns, and verbs. Second, this study examines the relationship between the participants' vocabulary acquisition and their video comprehension. The participants in this study were 44 proficient L2 learners and 39 less-proficient learners. These Taiwanese university participants joined a video-based CALL activity and completed follow-up vocabulary and comprehension tests. Quantitative analysis was conducted in terms of two proficiency groups with different English reading and listening abilities. The statistic results suggest that this activity significantly enhanced less-proficient participants' incidental vocabulary acquisition and comprehension. Both proficient and less-proficient groups made significant progress in incidental vocabulary acquisition. Through the activity of viewing video-based lessons, both proficient and less-proficient participants acquire nouns and verbs incidentally better than adjectives. Two proficiency groups of participants' vocabulary acquisition were positively related to their video comprehension. (Contains 6 figures and 6 tables.)