Portable impress videos don't play

I have many presentations on impress with embedded videos and animated gifs. When I use this presentations in the latest version of portable impress from a usb drive at a classroom the videos won’t show and a grey square appears instead. It is a classroom desktop computer that has no libreoffice installed, thus I use portable libreoffice.

Any help would be appreciated.

LibreOffice has no built-in media support for audio/video data. It relies on OS media framework, which means that if a file could be played or not depends on the specific system (e.g., OS version, or installed media packs).

Thanks, that clarifies things. Since the computer in question has Windows OS installed (Windows 7 I believe), would it be better to work with mp4, or avi? Thanks again.

No problem with Mike’s answer.
However I believe that Impress is rather weak in the handling of videos. I am currently using the latest version 64-bit on Windows 10 which is also completely up-to-date. In some previous versions it seems that MP4 videos were fairly consistent and played well. However, lately I have encountered a number of times when a video would not play in Impress but was just fine in Microsoft Powerpoint and VLC Player. I think this kind of indicated that the basic system configuration is correct and proper codecs available. For some unknown reason the videos just would not work in Impress - sometimes. I haven’t been able to come up with a definitive case that could be submitted as a bug report. Just kind of hit-or-miss. If I have a case where I need consistency I’m afraid that I have to revert to PowerPoint.

I think this kind of indicated that the basic system configuration is correct and proper codecs available

No. That just indicates that VLC does not depend on any external codec (it has everything it needs inside), and PowerPoint uses Windows Media Format SDK to use MPEG-4 version 3, which is possibly not a problem for MS product, but a problem for an open-source LibreOffice (see https://docs.microsoft.com/en-us/previous-versions//ms787745(v=vs.85)?redirectedfrom=MSDN and Windows Media Format 11 SDK - Win32 apps | Microsoft Docs)

In any case, this situation kind of defeats the “portability” purpose of libreoffice portable. If I run impress portable is precisely because I am using computers others than my own, so I cannot foresee what codecs/drivers must be installed for impress to run videos that would run fine on my system otherwise.
It is supposed to be portable right?
I tried installing VLC as a portable app alongside libreoffice, but do not know how to make it work or even if it would work at all.

Of course, you are right wrt non-portable nature of Impress; well - portable version is an independent project (although the one from PortableApps is advertised on the main site, and even kept in our download archive :-D)

LibreOffice does not use VLC, so installing it alongside doesn’t help in any way.

There was a GSoC project to use VLC in LO, but at that time, it was considered failed. There’s some incentive to re-visit this… but don’t hold your breath.

Great info - Mike, I have wondered who uses what.
However, I have seen video files that Impress will put out an error message for an mp4 file that says “The format of the selected file is not supported” but all other video players on my system do play with no problem (PowerPoint, VLC, Windows Media Player, Windows Movies & TV, MPC-HC).
It would be great if there was a project to allow use of VLC within LO. That should be good for both Windows and Linux users?
Thanks for the info!