Can you post a link to a public page that doesn't require authentication (log in) to access it?

Did you check the the server sends the file with the correct MIME type?

• 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://en.wikipedia.org/wiki/Use_of_Ogg_formats_in_HTML5

Apache:

AddType audio/ogg oga ogg
AddType video/ogg ogv
AddType video/webm .webm

A good place to ask advice about web development is at the MozillaZine "Web Development/Standards Evangelism" forum.

• http://forums.mozillazine.org/viewforum.php?f=25

The helpers at that forum are more knowledgeable about web development issues.
You need to register at the MozillaZine forum site in order to post at that forum.

Here's a screen grab, taken just a few moments ago, that show a similar problem:

Screen Shot

That is not HTML5, but a simple Flash player on the lbpost.com site.

• www.lbpost.com/life/sander/1309300324

Looks that you are blocking some content if you do not see the iframe with the SoundCloud Flash player.
Does this link have the same problem?

Having trouble viewing the SoundCloud player? Click here.

• http://soundcloud.com/sanderis/long-beach-arts-candidate

Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

The Soundcloud page works perfectly.

I restarted in safe mode, but the LBPost page still did not display the embedded player.

Just to clarify, when you click on 'share' at soundcloud, there are two main choices: HTML5 and Flash. The flash version works perfectly, but the HTML5 version does not. (See image below)

The video tag only works with a supported MIME type like video/ogg or video/webm

• https://developer.mozilla.org/En/HTML/Element/Video

I'm sorry, but I have no idea what video tag you're referring to. This is the code that soundcloud's system produces:

<iframe width="100%" height="166" scrolling="no" frameborder="no" src="http://w.soundcloud.com/player/?url=http%3A%2F%2Fapi.soundcloud.com%2Ftracks%2F40605063&auto_play=false&show_artwork=true&color=8c00ff"></iframe>

I don't see any video tag here.

Same here. I have noticed that soundcloud HTML5 players don't show up in any window or iframe on Firefox, whereas they display and work properly on Chrome and Safari (running on Mac OS X 10.7.3).
I have emptied every cache possible, restarted in safe mode, and it still doesn't work.
The basic flash player works perfectly fine in every browser.
Every browser is up to date.

Example :
http://www.wearethebeat.co.uk/2012/04/mr-pinks-disco-discharge-promo-mix.html

(image 1 : Firefox)
(image 2 : Chrome)
(image 3 : Safari)

Works fine here on Linux with Firefox 11 and Firefox 12 (beta).

Did you try to clear the cookies as well?

That fixed it. Just forgot to clear the cookies. I thought I had done it. Thanks a lot!

You're welcome