The video embed appears to be broken. On the dev branch, if I run Sample_03_Video.php and attempt to open the pptx I get an error.

The xml looks a bit different than a slide that I manually add a video to. The odp file is also not working, but I am mostly looking at pptx. I am on PowerPoint 16.54 on a mac. I am attaching my sample (testvideo.pptx) and the output from the sample (Sample_03_Video.pptx).
Sample_03_Video.pptx
testvideo.pptx