A "video poster presentation" sounds like a logical impossibility, but now that conferences are online, they seem to be a thing. What makes one effective? How is this different from a recorded conference talk? What makes for good content?
I am specifically answering the question of video poster presentations. This is not advice about making good videos or demos in general.
An in-presence poster presentation is a short oral presentation in front of a poster, with questions. The poster itself is a large surface usually divided into a small number of panels that the presenter can point to. You can functionally replace the oral poster presentation by a pre-recorded video, replacing the individual panels by a matching number of slides, and shedding a tear for the lost opportunity to answer questions.
Our practice therefore is to treat video posters as 5-minute oral presentations.
We find that the hard part is fitting a high-impact presentation into that time frame, whether it is for a poster or not. For guidance we use Christopher Lortie's ”Ten simple rules for short and swift presentations” from PLoS Comput. Biol. 13(3), https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1005373.
- Plan a clear story
- Provide only one major point per slide
- Limit use of text
- Use simple visuals
- Develop a consistent theme
- Repeat critical messages twice using different visuals
- Use the principle of parsimony in explanations
- Allocate more than one slide to effectively end the narrative
- Use the final slide for contact information and links to additional resources
- Use timed practice
First, this answer isn't based on experience of creating such things, but just on general principles. I assume that you want an audience to actually watch the video to the end and that what you have to say isn't so earth shatteringly novel and important that they naturally will. But also, I assume that what you want to say has value in itself, though more for some than others.
First, I think you have about 15 seconds at the start of the presentation to answer the viewers question "Should I continue with this or not?" But the answer has to be obvious from the presentation, rather than just saying outright "This is why you should watch." If you aren't immediately compelling, people will hit the "next" button. It isn't like a class where students are forced to sit and watch.
The last 15 seconds are probably also very important so that people have a succinct message to carry away - make it memorable.
Talking heads are boring. A video has an advantage over a live talk, of course, since interested watchers can hit rewind if they miss a point, but still, do something to avoid the talking head issue. An overly pedantic presentation will probably also induce watchers to move on.
I assume that the most interested people will have some way to contact you after the presentation so that you can get follow up. The format suggested by walkar in a comment sounds like it might be very good, so that people can ask questions after viewing and possibly get some synergy going. But I also assume you don't have control over format.
I'd suggest, actually, that you take some inspiration from an early science oriented TV show intended for children: Watch Mr. Wizard. It was a half hour of simple science done live. The wikipedia article points to some similar things that this show inspired. Some of the shows are available on [YouTube[(https://www.youtube.com/results?search_query=Mr.+Wizard). And note that by using another person, in this case a youngster, as an assistant, Don Herbert avoids the talking head problem. You can have a "conversation" with an assistant that you can't have with the audience.
Background: I'm an old guy with hearing problems. I don't watch TV or depend on video much. When I do, I'm looking for visual impact and am quick to move on if the presentation starts out too slowly or gets boring. On the other hand, I'm interested in lots of things. If you catch me early, I might stick around. I don't need to take notes anymore, so won't, but a clear message about the key insight (the last few seconds) will stick with me and make you memorable.
Oh, and I never missed an episode of Mr. Wizard.
Online poster presentations are displayed on a small screen. Usually the user interface makes it hard or impossible to zoom and scroll. Therefore, poster graphical design does not work. Instead, large fonts and a much smaller number of images should be used. Essentially, the poster should look like a slide instead of a poster.