This study assessed the effect of design instructional video based on the Cognitive Theory of Multimedia Learning by applying segmentation and signaling on the learning outcome of students in an online technology integration course. The study assessed the correlation between students' personal preferences (preferred learning styles and area of specialization) and their learning outcomes. A three-group pretest--posttest design was employed to assess whether there were significant differences in students' test scores after they watched an instructional video. The results of the analysis of covariance (ANCOVA) analysis indicate that instructional design had a significant effect on students' learning outcome. This effect was demonstrated by the statistically significant differences in students' learning outcomes, with the highest scores achieved by students in the segmented and signaled video group and the lowest scores in the no-segmentation and no-signaling group. Moreover, results indicate that students' learning preferences and area of specialization related significantly and positively to their learning outcomes. These findings suggest that the use of educational video in online courses has the potential to effectively improve students' learning outcome; however, it requires design manipulation. The results also emphasize the importance of rethinking the one-size-fits-all approach in developing online course content and include consideration of the students' learning preferences and area of specialization to optimize their learning.