Embedded MP4 video in PDF not working

Hi

Someone has kindly embedded an MP4 video that I created in a PDF for me. It works and plays absolutely fine on my laptop but I cannot get it to run on my primary desktop machine.

Both machines are running version 2023.006.20320

The only difference that I can see is that in Preferences -> Multimedia (legacy) -> Player Options the laptop has a checkbox (which is checked) for 'Show Multimedia Controls'; this simply does not exist on the desktop (see attachment).

I have now tried uninstalling, downloading and reinstalling Reader several times on my desktop and am completely stuck.

I would be very grateful for any help or insight that anyone can offer.