No sound in videos played in Tor Browser started by Thunderbird

For example: https://tails.boum.org/install/win/usb/#animation

I get in the journal:

Sep 29 17:39:33 amnesia thunderbird.desktop[10809]: [Child 10016, MediaPlayback #1] WARNING: 71c56309cdc0 OpenCubeb() failed to init cubeb: file /var/tmp/build/firefox-944a0bc18ba6/dom/media/AudioStream.cpp, line 375
Sep 29 17:39:33 amnesia thunderbird.desktop[10809]: [Child 10016, MediaPlayback #1] WARNING: Decoder=71c56616ca00 [OnMediaSinkAudioError]: file /var/tmp/build/firefox-944a0bc18ba6/dom/media/MediaDecoderStateMachine.cpp, line 3385

The log mentions thunderbird but I’m trying to watch the video in Tor Browser.

The same happens on YouTube and Vimeo.

Feature Branch: bugfix/17105-torbrowser-started-from-thunderbird

Related issues

Blocks #16209

Original created by @sajolida on 17105 (Redmine)

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