libreimpress for presentation. I came to the case on inserting mp4 video, but not supported. I found out that likely relates to gstreamer plugin, so a simple fix is to install gstreamer plugins.
Run below command on ubuntu/linux mint
sudo apt-get install libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev libgstreamer-plugins-bad1.0-dev gstreamer1.0-plugins-base gstreamer1.0-plugins-good gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly gstreamer1.0-libav gstreamer1.0-doc gstreamer1.0-tools gstreamer1.0-x gstreamer1.0-alsa gstreamer1.0-gl gstreamer1.0-gtk3 gstreamer1.0-qt5 gstreamer1.0-pulseaudio
https://gstreamer.freedesktop.org/documentation/installing/on-linux.html?gi-language=c