Since the computers are introduced, there have been many meaningful attempts to use computers as education tools. Additionally, the wide use of web servers on the internet makes video-on-demand ser-vices available especially in the entertainment area. They also developed digital video lectures, which record video lectures as digital contents, and provide them also as parts of video-on-demand services. During the COVID-19 pandemic in the year of 2020, almost all schools around the world provided digital video lectures. Since the digital video lectures can provide high-quality lectures to lots of people at relatively-low costs, it is now expected to be much actively used in near future. In this paper, we will present more details of what preparations and choices are pos-sible, what to do, and what to avoid, in the process of providing digital video lectures, especially in the field of computer science. At this time, these kinds of literature surveys are seriously lacking, and thus, our case studies will be used to further improve the overall quality of digital video lectures and expand the e-learning markets. This paper will be a good starting point for providing check points and reference items to lecturers who prepare and provide digital video lectures.