Intellectually disabled (ID) students in secondary education are often taught in an individual setting where video instruction is used. Especially, when the instruction is about complex assignments, many students may forget parts of it. In this study, we tried to find out if prompting ID students to explain video instruction would help them to improve their performance. Research with regular students indicated that explaining instructional materials can be effective (Roy & Chi, 2005). In a first experiment with 41 ID students in Dutch secondary education, we varied the complexity of assignments and compared students who first watched and then explained video instruction of assignments (n=21) with students who watched twice but were not required to explain (n=20). It turned out that only for complex assignments, explaining to another person was more effective for students' task performance than just watch video instruction. In the second experiment with 58 ID students, we repeated the study with complex assignments. The students in the experimental group (n=29) improved more after explaining video instructions than the students who only watched videos (n=29). The experimental group also had a more complete mental representation of an assignment and could better assess how well they had performed it.