"Video player" App not working properly

I downloaded a Video from Youtube as test subject and it can not be played in the normal NC files view.
But when I use a share link, a different video player (the app) shows up and it works. The video can play. Only scrubbing is not possible.
You can test this with my test account here:

User: Support
PW: videoplayernotworking
Here the video as shared link:

I think the video player app is installed correctly. I deleted the files_videoplayer folder again, cloned the stable19 branch and assigned the www-data user, then enabled the app.
Anything I can do to make the app work in the files app aswell?

System Information

Nextcloud version: 19.0.3
Operating system and version: Raspbian GNU/Linux 10 \n \l
Apache version: Apache/2.4.38 (Raspbian)
PHP version_: PHP 7.4.10 (cli) (built: Sep 9 2020 06:54:34) ( NTS )

Simon Wolf

Just read this, maybe it is related to that issue?