These screencasts demonstrate how to calculate various statistics tests by hand. They were developed for the module PSY1205 Introduction to Statistics - a level 1 module in the School of Psychology at the University of Exeter. The course handbook was primarily written by others so I am unable to upload it here as present. However, each question is clearly visible in the screencast. Each screencast covers a particular question that students were set. Questions were devised by Prof. Andy Wills.
These two videos show you how to calculate an unrelated-samples t-test.