After rendering the movie shows only a black screen but with audio?
You could try a different video format.
Maybe put the video on dropbox and provide a link if you want specific feedback.
You might be using an outdated video player
My video player is fine and it can play other videos.
I downloaded video yesterday which can play as normal,
but today I tried 4-5 times it shows black screen every time.
PC: Mac OS Catalina 10.15.5
VideoScribe version: 3.5.2-18 Mac (OS X) PRO
A PNG confirms that the video looks black on your computer, but it doesn't help troubleshoot the problem with the video.
It is possible that you have installed some other program or codec which has interfered with the rendering process or the playback process.