Forgot to include the Flatpak info:

$ flatpak info org.mozilla.firefox

Firefox - Fast, Private & Safe Web Browser

         ID: org.mozilla.firefox
        Ref: app/org.mozilla.firefox/x86_64/stable
       Arch: x86_64
     Branch: stable
    Version: 141.0.3
    License: MPL-2.0
     Origin: flathub
 Collection: org.flathub.Stable

Installation: system

  Installed: 294.0 MB
    Runtime: org.freedesktop.Platform/x86_64/24.08
        Sdk: org.freedesktop.Sdk/x86_64/24.08

     Commit: 271e026c410fc2b80582a11266863ba69a2d7b407f73299aa6b5adac8eaabffe
     Parent: b37a095bd9d514dae72a8a13627de12d06ca6d32a5bc37838102bdf4cc14e8e0
    Subject: Export org.mozilla.firefox
       Date: 2025-08-07 12:37:46 +0000

edit: after posting this i realized i was still running the old 141.0.3 flatpak. after updating to i can now play the "1: HTML5 MPEG Video Test" at the test page and big buck bunny is working as well. Still no Luck with "3: HTML5 Ogg Video Test" and some embedded videos still don't play.

I have no issue with either site. see screenshot Not a browser issue, looks like you're missing something. What OS? What Desktop? X11 or Wayland? Does it happen with Firefox in Troubleshoot Mode?

Operating System: openSUSE Leap 15.6 KDE Plasma Version: 5.27.11 KDE Frameworks Version: 5.115.0 Qt Version: 5.15.12 Kernel Version: 6.4.0-150600.23.60-default (64-bit) Graphics Platform: X11 Processors: 16 × AMD Ryzen 7 PRO 6850HS with Radeon Graphics Memory: 62.1 GiB of RAM Graphics Processor: AMD Radeon Graphics Manufacturer: HP Product Name: HP EliteBook 865 16 inch G9 Notebook PC

Here's an AI answer.

After some more days of testing i am not any wiser. The video support blimps occasionally. And i cannot figure how that happens. I quit my Browser (e.g. when travelling and coding) and when i fire it back up the videos play. Then i restart it again and the support is gone again. Switching into troubleshoot mode does not change that. Restarting, both OS and flatpak, does not reliable restore video playback.

> Not a browser issue, looks like you're missing something. As far as i understand flatpaks are supposed to bring their own codecs. And since every non-firefox browser has no playback issues, i started looking into firefox as a source. >What OS? What Desktop? X11 or Wayland? Fedora Linux 42.20250821.0 (Sway Atomic) SwayWM as provided by the distro. No additions to the os-tree at all. org.mozilla.firefox Flatpak from Flathub

Does it happen with Firefox in Troubleshoot Mode? Yes. No matter what mode i use the error happens in all of them.

I tested some other flatpak browsers: working: app.zen_browser.zen com.opera.Opera org.qutebrowser.qutebrowser org.chromium.Chromium com.vivaldi.Vivaldi com.brave.Browser not working: net.waterfox.waterfox org.gnome.Epiphany(webKit/Safari based)

You are missing some needed packages for your distro. I would hit your distro forum and I'm sure it's easy fix. Waterfox also works for me. see screenshot

>You are missing some needed packages for your distro.

This would be true, if i would not use flatpaks. The codecs are supposed to be bundled with flatpaks. my base OS is not aware of multimedia at all. Still flatpaks like mpv, chromium-based browsers and so on are managing. addition: And as stated earlier the media support goes in and out when restarting firefox.

Even if i WOULD install h264/5 codecs on my system these codecs would not be available in the context of the flatpaks, since thats exactly the point of containerized applications. And thats the reason i am posting here and not to my distros support channels.

I appreciate your effort, but please read the information i provide as i do with your answers. 💕

Good luck.