This appears to be related to an upgrade to Ubuntu 22-04, but probably requires some tweak to LO to make it work. Since upgrading, every time I insert any video the slide becomes a black mess, and impress hangs. When I run an old presentation with embedded videos, the video is blacked out, and impress hangs. However, I have run previous version of Ubuntu with Appimage, and I now observe the same behaviour there too.
Ubuntu 22-04 and others