Online courses or online lectures are usually structured into several sequences and, in addition to the lecturer's videos, contain resources such as assessment problems or interactive demos [Guo et al., 2014].

The term video presentation or video lecture refers to videos an instructor creates in advance to complement their online courses or live performances or, as in our case, to replace live lectures due to the current corona pandemic. These videos have the same content and context as the lectures in face-to-face form but can be accessed from anywhere without being physically present. Usually they consist of the lecturer's slides and their audio recordings [Brecht, 2012]. To investigate the effect of video presentation on student’s content understanding, we distinguish between the three following types of video presentations:

• Lecturer is not visible
• Could be Powerpoint or any other presentation format, with voice-over and slides visible full screen [Hansch et al., 2015]
• Annotations on slide can be used to highlight information or draw the viewer’s attention to a specific detail [Hansch et al., 2015]

• Lecturer is visible
• Common style, typically shot in a studio [Hansch et al., 2015]
• Can be used to build a connection between the person on-camera and the viewer [Hansch et al., 2015]

• Lecturer is visible
• Ability to show slides and instructor at the same time [Hansch et al., 2015]

With „content understanding“ we define to what extent the students can absorb the content of the lecture and reproduce/use the knowledge they have acquired. For this purpose we design a questionnaire that the students will answer after watching the video.

The definition of and concept of e-learning will expand and mature over time as the needs for learning can undergo various alternations. However, in an international project with professionals as participants from all around the world a defintion was declared which has found general consensus: „E-learning is an approach to teaching and learning, representing all or part of the educational model applied, that is based on the use of electronic media and devices as tools for improving access to training, communication and interaction and that facilitates the adoption of new ways of understanding and developing learning.“ [Sangrà et al., 2012]

Within the project Higher education Online: MOOCs the European way, which goal it was to strengthen an open network for European cooperation on open education, the therm MOOC was definded as: „online courses designed for large numbers of participants, that can be accessed by anyone anywhere as long as they have an internet connection, are open to everyone without entry qualifications, and offer a full/complete course experience online for free“ [Jansen & Schuwer, 2015].

David Brecht, H. „Learning from Online Video Lectures“. Journal of Information Technology Education: Innovations in Practice 11 (2012): 227–50. https://doi.org/10.28945/1712.

Guo, Philip J., Juho Kim, und Rob Rubin. „How Video Production Affects Student Engagement: An Empirical Study of MOOC Videos“. In In Proceedings of ACM Conference on Learning at Scale (L@S, 4–5, 2014).

Sangrà, A., Vlachopoulos, D., & Cabrera, N. (2012). Building an inclusive definition of e-learning: An approach to the conceptual framework. International Review of Research in Open and Distributed Learning, 13(2), 145-159.

Jansen, D., & Schuwer, R. (2015). Institutional MOOC strategies in Europe. Status Report Based on a Mapping Survey Conducted in October-December 2014.

Hansch, Anna, Lisa Hillers, Katherine McConachie, Christopher Newman, Thomas Schildhauer, und Philipp Schmidt. „Video and Online Learning: Critical Reflections and Findings from the Field“. SSRN Electronic Journal, 2015. https://doi.org/10.2139/ssrn.2577882.