This study concerned multiple exposures to English before writing and aimed to explore the possibility of an increase in free active vocabulary with a focus on latent productive vocabulary beyond the first 2,000 most frequent words. The researcher incorporated online video into her college freshman composition class and examined its effects on non-basic vocabulary use. To activate previously known vocabulary, a variety of audiovisual modes before writing were applied to four groups alternately: (1) video with captions, (2) video without captions, (3) silent video with captions, and (4) video with screen off (soundtrack only). The results show that the writing involving non-captioned videos contained a higher percentage of advanced vocabulary than that with the other three conditions (specifically, 12.45% versus 11.33% with captioned videos, 5.2% with silent but captioned videos and 8.63% with audio only). Drawing upon the dual-coding theory, this study also points out some pedagogical implications for a video-based writing course.