[_up]

You could just use Hotkeys <ctrl>+<alt>+<r> to start video recording on Windows. And then use some free Video editor. Davinci Resolve also has professional audio and compositing features and is free.

If you don't know what you are doing, I would suggest you probably should just hire some freelancer on Fiver, license professional Music and find a Voice over.

I think a good Video can do much more than just explain your product it also can make people trust you more. But a badly produced Video can also do the opposite and make people think also bad about your Software. On the other hand, a simple App probably needs a lot less trust than a Cloud Service.