What is the workflow/steps you are doing to add the video to the PDF file? A small video recording of the same would be very helpful. Make sure you have version 22.1.20169 installed. Go to Help > Check for updates and reboot the computer once.
What are the steps the users are doing to open the PDF file? If they are opening it in a web browser, please ask them to download it to the computer locally and then open it via Acrobat/Reader DC application and check.
Also, please share the PDF file in question so that we can check it at our end.