• The informality of video essay narration engendered ideation in drafting and script writing for students. • Students felt more responsible and personally invested in their arguments when they narrated and dramatized them in the video making process. • While students admitted that they tended to “gloss over” written drafts when revising, the video making process prompted students to be more self-motivated in the revising process, enabling them to evaluate and develop their arguments. • Unlike oral presentations, as students viewed their video essays as audience members, they could more clearly discern if their arguments lacked coherence or depth. This self-evaluation resulted in students taking the initiative to revise their final written assignments. Although multimodal assignments have increasingly been incorporated into academic writing curricula, research into their impact on student writing remains limited. This study, conducted at a Singaporean university, required students to transform a written essay draft into a video essay and then revise their draft into a written essay assignment. By comparing students’ initial drafts and their final submissions, and analysing interviews and reflective journals, we identified significant benefits stemming from the transmediation between written and multimodal text. Specifically, we found that 1) transmediation enabled students to self-evaluate their writing as they repeatedly listened to their voiceovers, found concrete visuals to illustrate their ideas, and edited their work to fit the concise video format; 2) students broke with habitual, less useful revision practices as they were freed from the conventional and grammatical concerns of written academic text and narrated their arguments colloquially in their voiceovers; 3) students exhibited an improved awareness of audience and medium; and 4) students were more enthusiastic with the course due to the novelty of the multimodal assignment. These findings suggest that including a video essay assignment during the drafting process can serve as an effective tool in advancing students’ abilities to evaluate their own academic writing.