If handbrake scares them, don’t you dare to demonstrate how to use ffmpeg. I remember when I used handbrake for the first time and thought “wow, it’s much more convenient than struggling with ffmpeg”.
Handbrake's UI is in the uncanny valley for me -- too complicated for use by laymen, and way too limiting for use by people who know what they're doing...
A "normal person" is just someone whose time and mental energy are focused on something other than the niche task your app is aiming to solve. With enough time and focus, anyone can figure out any interface. But for many, something which requires a smaller investment to achieve the results they need is preferrable.
Also, even the most arcane and convoluted interfaces become usable with repetition. Normal people learn the most bureaucratic business workflows and fly through them if that is their job. Then if you dare to "improve" any aspect of it you will hear them complain that you "broke" their system.
Well yes you force them to find other workarounds because their current workaround are no longer relevant. Because no system will ever fit everyones usecase.