Do short screencasts improve student learning of mathematics?

'I really like this form of support. I would be delighted to [...] see any and all topics covered by such screencasts.' The above comment was made by an MSc student after watching two screencasts on undergraduate calculus. They were produced as part of an MSOR Network funded mini-project to develop and evaluate screencasts on advanced calculus topics. The sentiment expressed was reflected in many other students' comments. This paper reports the outcomes of this project.