Recently, researchers have compared the effectiveness of video-based instruction (VBI), particularly video modeling, when using smaller versus larger screen sizes with positive, but mixed results. Using an adapted alternating treatments design, we compared two different screen sizes (i.e., iPhone 5 versus iPad 2) using video prompting as the VBI strategy. Three secondary students with autism spectrum disorder (ages 16-18 years) participated. Our results suggest that both screen sizes were effective with two participants while the larger screen size was more effective for one participant. These results are discussed along with implications for professionals implementing video prompting on mobile devices.