This page provides guidance on writing good video slides.
From What is code profiling in "Writing Efficient R Code". As well as having the instructor dressed up to match the dataset being discussed, this also makes good use of images and screenshots.
From Embrace, Extend, Override in "Object-Oriented Programming in R:S3 & R6". This makes use of a physical prop in order to demonstrate the concept. It also includes a summary slide at the end.
How many slides should I have?
Too few slides can be boring; too many can be overwhelming. A reasonable heuristic is to have "one slide per idea". That is, anytime you introduce a new idea in words, you also change what is onscreen.
Whether they are pictures, plots, or diagrams, having images in your videos helps students learn, and makes the course adverts more photogenic, which helps to increase the number of students starting your course.
Use dual coding
When words and visuals match ("dual coding"), it can increase learning relative to a single communication channel.
Include a summary slide
It can be hard to remember everything that is spoken in a video. Having a summary slide can help students to be aware of what they just learned.
Common problems and their solutions
Too much information
Videos need to be understandable in real-time, so err on the side of simplifying things and omitting things.
Speech and slide mismatches
While complementary speech and slides provide a boost to learning (see "Use dual coding" point), having mismatched speech and slides detracts from learning, since the student has to decifer which to the two media is the one to pay attention to.
Using "meme" images
These often get dated incredibly quickly, and detract from the premium feel of the content.