One of the advantages of explaining something in video form is that you can put details or supporting evidence in the visuals rather than in the voice-over. I call this technique “homework on screen” (at least, until I find a better phrase). The voice-over can summarise something quickly, knowing that viewers can pause the film and look through the details if they wish.
The first time I realised how useful this could be was when during an early side project: a film arguing that having political party members choose their leaders was a bad idea.
The problem was this: I wanted to start the film by quickly establishing that in the UK the leaders of political parties are elected by party members. While this is true, it’s a simplification and I felt politics nerds would get distracted by this simplification (for example, in the Conservative Party, MPs decide the final two candidates that members choose from). Yet at the same time, I didn’t want to spend lots of time going through all the details in the voice-over.
The simple solution was to show a diagram of the process alongside voice-over saying, “Party leaders are chosen — bar a few initial hurdles — by party members.” Any viewers who wanted the details could pause the video to check them, while other viewers would be reassured I had evidence for my summary of the process.
Here are some more examples:
In the intro to this explainer about Seltzer, Adam Freelander shows a graph illustrating Seltzer’s rise in popularity. While he could have talked about an “increase of 100 million gallons from 2007 to 2016”, all he does is say, “Here’s a chart. Seltzer then. Seltzer now.” This breezy summary is enough for most of the audience and if it isn’t, they can pause the video and examine the details. (Watch it, it’s a great video.)
Explainer king CGP Grey uses this technique frequently, usually to add interesting extra detail rather than supporting evidence. In the example above (from the wonderful explainer How to Become Pope) the voice-over describes the process by which cardinals vote for their choice of Pope (“Write down one name on a piece of paper, and stand before the altar, and say a long Latin phrase, before officially casting the ballot”). The visual shows a translation of the phrase at the exact point the voice-over references it (3:53).
In this second example, the voice-over states, “It’s tradition to take the name of a previous Pope”, while showing a graph of which Pope names have been chosen in the past (4:21). In both cases, the visuals add some interesting extra detail without slowing down the overall pace of the film.
I love this example from a video about London’s boroughs by Jay Foreman. His caption even acknowledges that people often pause YouTube videos to look at the detail in explainers visuals.
This is from Why does London have 32 boroughs? (also by Jay Foreman) and shows the opportunity this technique provides for sharing extra facts.