No audio during video playback

STR:

1. Try to play a video with audio, for example:

https://media.libreplanet.org/mgoblin_media/media_entries/2070/FSFKeynotewithSlidesHighRes.ogg

EXPECTED: The video should play with audio.

ACTUAL: There is no audio and a notification shows up saying: "To play audio, you may need to install the required PulseAudio software" + button "Learn how". But pulseaudio is already installed and works with other apps:

[~]: rpm -q pulseaudio pulseaudio-9.0-8.1.x86_64

Security level is set to "Safest"

Trac:
Username: heyjoe