Turning a LaTeX beamer presentation with movies into a portable PPTX via LibreOffice.

Use case: your talk venue insists you use their computer. And PowerPoint.

You'll need pdftoppm (or similar, comes with poppler) and FFMPEG if your movies still need conversion. And a recent Impress (mine was LO 7.4.4.2). Older versions crashed on saving as PPTX if there were embedded media. 

First, create page images, in bash:
pdftoppm mypresentation.pdf img -png -r 250

The output is a series of img-1.png, ...,img-n.png. Resolution is here 250.

If necessary, convert all movies (let's assume they're .avi) to something PowerPoint/Impress will digest. Other containers and codecs might work as well, but my Windows failsafe is WMV2.

ffmpeg -i input.avi -codec:v wmv2 -b:v 2000k output.wmv 

Batch conversion:
for m in *.avi; do ffmpeg -i $m -codec:v wmv2 -b:v 2000k ${m%avi}wmv; done 

Start a new Impress presentation, and add a photo album via the Insert->Media menu (see screenshot).

At this point it's a good idea to protect position and size for all images in the slide (Properties sidebar). This is probably scriptable, but I'm not researching it today. Add the movies on top of the slide images. Note: Videos added via drag and drop from a file browser will get linked and not embedded into the PPTX. To embed, you need to go via the Insert->Audio or Video... dialog. Save as PPTX.

Note: I tried importing PDFs directly into Impress but that only opened them in Draw .