Downloaded the the source from Github (kstars and indilib) and build them on Linux.
I get now a different behavior from the stable windows client, the video window is shown for a fraction of a second and then it disappears.
On the log I see:
2017-05-27T18:24:40: Error capturing video stream.
2017-05-27T18:24:40: Error capturing preview: Unspecified error
2017-05-27T18:22:42: Starting the video stream with single frame exposure of 15.000000 seconds.
When running on Linux (ubuntu) or when building from source do I require some special libs for the video window to work ?
I've followed the dev tutorials and installed the listed dependencies.