Multiple confusing behaviours playing video

[davidatMB]

No Sound

I included a mp4 video like this
[video muted=1 width=20% height=20% url="http://localhost/api/endpoint/slide/asset/slide_get_asset.php?id=ec495295e0499d546ceee89bf8183235&name=Grundschule.mp4&hash=93b0326b8b8163e830b0873f554fba8e"][/video] .
When I open editor view and select the slide where the video is in, sound is played.

But when I Display the slide ("localhost/app/?queue=") no sound is played (I know what muted means (-:, but everything other won't work either).

Video only playing if ...

The video is only played, if

• under "Animation" must something other than "No animation" selected - nothing (even no "normal" content) is shown
• the argument "muted" must be set to 1 - everything other than 1 and the video doesn't playing (only the 1.frame is shown)

I'm using the latest build of LibreSignage Docker image (right now its Version 1.2.0).
On Ubuntu 18.04