Firefox does have some known HTML5 compatibility issues.

To see what Firefox can and can't do, take the HTML Test.

Hopefully these HTML5 issues will be addressed in future updates.

Try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• You can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.
• Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

Please report back soon.

Based on a quick look, the site is designed to first offer MPEG-encoded media, then OGG-encoded media. If the controls disappear, this could indicate that Firefox was not successful with one or both of these formats.

Starting in Firefox 21, MPEG media can be played directly by Firefox rather than handed off to a plugin such as the Flash player. Maybe there is a problem with Firefox accessing the Windows Media components it needs for this? You could try switching it off and see whether that makes any difference. Here's how:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the filter box, type or paste media and pause while the list is filtered

(3) Double-click media.windows-media-foundation.enabled to switch its value from true to false. Not sure whether this takes effect immediately when you reload the tab you were in or whether you need to restart Firefox before it takes effect.

Any difference?

I tried with safe mode and about:config settings, in both cases nothing happens. The images uploaded shows how the controls appear and what happen one second after.

Any other advise?

This can happen if Firefox isn't able to play or retrieve the media file.

Any errors about playing audio files in the Browser/Error Console (Ctrl+Shift+J) or Web Console (Ctrl+Shift+K) (Firefox/Tools > Web Developer)?

There is no errors in the console and according to http://html5test.com/ Firefox can play ogg audio files and the site with the problems offers the audio in two formats: mp3 and ogg.

Extract from http://www.teamrockradio.com/shows/the-metal-hammer-magazine-show

 <div class="on-demand-show-audio clearfix">
    <audio controls preload="auto">
      <source src="http://teamrock-radio-ondemand.s3.amazonaws.com/metal-hammer/2013/09/MHshow-03-september.mp3" type="audio/mpeg">
      <source src="http://teamrock-radio-ondemand.s3.amazonaws.com/metal-hammer/2013/09/MHshow-03-september.ogg" type="audio/ogg">
      <p>Hmmm, your browser doesn't appear to support the HTML5 <code>audio</code> element. We'd recommend upgrading your browser to the latest version of Google's <a href="http://www.google.com/intl/en_uk/chrome/browser/" target="_blank">Chrome</a> browser if possible.</p>
    </audio>
  <span>Listen again</span>
  </div><!-- end on-demand-show-audio -->

That is a problem with the configuration of the server that sends the ogg file as "binary/octet-stream".

• https://developer.mozilla.org/en/Media_formats_supported_by_the_audio_and_video_elements
• https://developer.mozilla.org/en/Configuring_servers_for_Ogg_media

HTTP "Content-Type" of "binary/octet-stream" is not supported. Load of media resource http://teamrock-radio-ondemand.s3.amazonaws.com/metal-hammer/2013/08/MHshow-28-august.ogg failed. @ http://www.teamrockradio.com/shows/the-metal-hammer-magazine-show

The Nightly 26a1 build supports MP3 for me on Linux and it works with that format.

Okay, that makes sense. The Windows Media Foundation was added in Windows Vista, so on Windows XP, Firefox was falling back to the OGG stream. I didn't test that myself.

There might be an add-on which can correct the content type of the stream so Firefox can play it, but I'm not aware of one off the top of my head.

• Bug 861693 - DirectShow backend for MP3 decoding on WinXP (Firefox 26)

I'm not aware of a way to modify response headers apart from using proxy software.
Best would be to contact the website and ask them to correct the MIME typwe send by the server.

You can point them to the MDN article.

• https://developer.mozilla.org/en/Configuring_servers_for_Ogg_media