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Why does Firefox not play a webm video until the complete file is downloaded?


Firefox won't start playing webm videos until the complete video is in downloaded/cached.

http://lac.linuxaudio.org/2013/video.php?id=78 <-- example video or http://lac.linuxaudio.org/2013/recordings/09-02-baalman-480p.webm

Server side seems fine: Content-Type is OK (video/webm), apache2.2.22 (returns 206 for Range:0- requests),..

Problem exists with

* Nighly 24.0a1 (2013-05-17) Linux 32bit
* Firefox 21.0
* Iceweasel (10.0.12 from debian)

Works fine with other browsers (e.g. chromium, epiphany,...) Might be similar to https://bugzilla.mozilla.org/show_bug.cgi?id=502894#c1

Is this a bug? An issue with HTML5

Thanks in advance

Additional System Details

Installed Plug-ins

  • MozPlugger version 1.14.3, maintained by Louis Bavoil and Peter Leese, a fork of plugger written by Fredrik Hübinette.For documentation on how to configure mozplugger, check the man page. (type man mozplugger) Configuration file:/etc/mozpluggerrc Helper binary:mozplugger-helper Controller binary:mozplugger-controller Link launcher binary:mozplugger-linker
  • Version:
  • Google Talk Plugin Video Accelerator version:
  • Version 1.1.11 The Luggage, copyright 1996-2007 The VideoLAN Teamhttp://www.videolan.org/
  • This plug-in detects the presence of iTunes when opening iTunes Store URLs in a web page with Firefox.
  • Gecko Media Player 1.0.4Video Player Plug-in for QuickTime, RealPlayer and Windows Media Player streams using MPlayer
  • DivX Web Player version
  • The Totem 2.30.2 plugin handles video and audio streams.
  • Shockwave Flash 10.3 r181
  • The next generation Java plug-in for Mozilla browsers.
  • Helix DNA Plugin: RealPlayer G2 Plug-In Compatible version built with gcc 3.2.0 on Jul 26 2007


  • User Agent: Mozilla/5.0 (X11; Linux i686; rv:21.0) Gecko/20100101 Firefox/21.0

More Information

Amit Kumar Thakur 83 solutions 863 answers

Recent crashes of certain multimedia contents (this includes Youtube videos, certain flash games and other applications) in conjunction with Firefox are most probably caused by a recent Flash 11.3 update and/or a malfunctioning Real Player browser plugin.

In order to remedy the problem, please perform the steps mentioned in these Knowledge Base articles:

Flash Plugin - Keep it up to date and troubleshoot problems

Adobe Flash plugin has crashed - Prevent it from happening again

Flash 11.3 doesn't load video in Firefox

Other, more technical information about these issues can be found under these Links:



Please tell us if this helped!

Question owner

There is no flash involved.

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10776 solutions 96959 answers

Helpful Reply

I see the same happening and the full video (?) gets loaded.
If I disable WebM (media.webm.enabled -> false) then I get the Gecko media player plugin that displays the video after a short buffering.