From a recent MIT study on edX video...
Research Question: How does video production affect student engagement in MOOCs?
1. Shorter videos are much more engaging. Engagement drops sharply after 6 minutes.
Recommendation: Invest heavily in pre-production lesson planning to segment videos into chunks shorter than 6 minutes. This is the most significant recommendation!
2. Videos that intersperse an instructor’s talking head with PowerPoint slides are more engaging than showing only slides.
Recommendation: Invest in post-production editing to display the instructor’s head at opportune times in the video. But don’t go overboard because sudden transitions can be jarring. Picture-in-picture might also work well.
3. Videos produced with a more personal feel could be more engaging than high-fidelity studio recordings.
Recommendation: Try filming in an informal setting such as an office to emulate a one-on-one office hours experience. It might not be necessary to invest in big-budget studio productions.
4. Khan-style tablet drawing tutorials are more engaging than PowerPoint slides or code screencasts.
Recommendation: Introduce motion and continuous visual flow into tutorials, along with extemporaneous speaking so that students can follow along with the instructor’s thought process.
5. Even high-quality prerecorded classroom lectures are not as engaging when chopped up into short segments for a MOOC.
Recommendation: If instructors insist on recording traditional classroom lectures, they should still plan lectures with the MOOC format in mind and work closely with instructional designers who have experience in online education.
6. Videos where instructors speak fairly fast and with high enthusiasm are more engaging.
Recommendation: Coach instructors to bring out their enthusiasm and reassure them that they do not need to purposely slow down. Students can always pause the video if they want a break.
7. Students engage differently with lecture and tutorial videos.
Recommendation: For lectures, focus more on the first-time watching experience. For tutorials, add more support for rewatching and skimming, such as inserting subgoal labels in large fonts throughout the video.
Full article: http://pgbovine.net/edX-video-production-research.htm