Videos disappear when I open a .pptx file containing videos within slides. From the insert menu there is no option to insert video, nor can I find any other means of adding a video to a slide. I came to the conclusion that you could not add videos to Stage until I read this on the Stage info page...

Calligra Stage is a powerful and easy to use presentation application. You can dazzle your audience with stunning slides containing images, videos, animation and more.

Is there a way to add videos?

In the "Add Shape"-docker, there is a button with some shape symbols on it at the right. Press this button, and in the appearing popup select "Video" (from the default category).

If you don't have the "Add Shape"-docker, you can change its visibility using the menu: "Settings"->"Dockers"->"Add Shape".

Thank you, that worked. Is it possible to play the video automatically when changing slides? I have broken a video into multiple segments and would like to play the video and hold the last frame, then switch to the next slide and essentially resume playing from where the first video stopped.

I don't think that this is possible, and if it is I don't know how to do it, sorry.
(As long as you do not want to manually pause and play the video during the presentation )

Thanks sebpe, working in kubuntu 20.04 , Calligra Stage 3.1