How to convert LibreOffice Impress to video with custom animations?
I would use a screen recording / capture tool. With this solution you can even define your individual timing from slide to slide.

Which software to use? Depending on your operating system there are many free or low cost solutions available. There are even web-based services.

This blog post lists 10 of them. I copied that list here for reference.

Desktop Software:


IceCream (Windows)
ActivePresenter (Windows)
CamStudio (Windows)
Snagit (Windows/Mac)
Jing (Windows/Mac)


Web Services:


Webinaria
Apowersoft
Screenr
ScreenToaster
ScreenCastle


I'm sure next year there will be different options. That's why this list can only be an overview and starting point for your own research.

You might need another tool to finally crop your recorded video to 1280x720 or 1920x1080 pixel, because the screen recorder might have recorded an odd rectangle that you have drawn with the mouse. My favorite is VirtualDub for Windows.