Whether a demo is helpful really depends on the audience, the nature of the presentation, and what points you are trying to get across. It's just one of a numbe

Whether a demo is helpful really depends on the audience, the nature of the presentation, and what points you are trying to get across. It's just one of a number of rhetorical devices. For example in sales presentations to C-level managers it's generally better to avoid a demo and just assert the product works and sell the benefit to the business. When selling to technical folks demos are often a critical part of the pitch to show you are for real. Videos make it look as if you either don't know the technology or are afraid to show the product in action. This is all part of basic rhetoric. If in doubt, just ask: what would Cicero do?