This paper investigates the effect of mobile phone screen size (1.65 inches - 2.75 inches) on video based learning. It first examines the educational benefits of video as a teaching medium and surveys the usage and issues related with video based learning. After which, it investigates the value of video for mobile learning. It reports on an empirical investigation that studied the effect that screen-size has on video-based m-learning. Findings indicate that regardless of the screen size of a mobile phone, students tended to have a positive overall opinion of m-learning and watching the video significantly increased their knowledge of the subject area. However, if an m-learning environment that relies heavily on video based material is displayed on a mobile device with a small screen, such as an average mobile phone, then the effectiveness of the learning experience may be inhibited. Paper identifies the underlying reasons why mobile phone screen size may be a problem for video based mlearning. The implications of this finding are discussed.