Sometimes, the video or audio content in a web page cannot be properly downloaded and displayed in Firefox. A required plugin may be missing, outdated, blocked, in conflict with another plugin or extension, or the content may be blocked for some reason. This article will help you solve these problems.

Note: If you're having trouble with a website, click the padlock icon in the address bar to see if Firefox has blocked insecure parts of the page. See Mixed content blocking in Firefox for details.

HTML5 audio and video

Firefox has built in support for open media formats usually associated with WebM, Ogg and Wave containers. However MP3 and MP4 containers usually depend on platform decoders for MP3, AAC and H.264 audio and video streams. For more information, see Fix video and audio problems on Firefox for Windows N editions and HTML5 audio and video in Firefox.

Plugins

Install missing plugins

Although Firefox is able to handle certain HTML5 audio and video content on web pages, it may need the help of media players and browser plugins for other content. Although you may have the correct media players installed to play video and audio files, you may be missing the necessary plugins when the media is embedded within the web page itself.

• Flash plugin: See Install the Flash plugin to view videos, animations and games and Flash Plugin - Keep it up to date and troubleshoot problems
  • The Flash plugin is used for embedded audio and video on many websites.
• Java plugin: Use the Java plugin to view interactive content on websites
• Silverlight plugin: See Use the Silverlight plugin to play audio and video
• Windows Media Player plugin: See Play Windows Media files in Firefox with the Windows Media plugin
  • The Windows Media Player plugin will only play a specific few Windows media formats (.asf, .asx, .wm, .wma, .wax, .wmp, .wmv, and .wvx) unless the web page is specifically designed for Firefox and other Mozilla browsers.
• QuickTime plugin: See Use the QuickTime plugin to play audio and video
  • The QuickTime plugin can handle many different types of embedded media. On older operating systems, the QuickTime plugin may not be configured to handle some common file formats found online, such as embedded .mp3 audio on Windows XP. In such cases, you need to select the media formats you want QuickTime to play in Firefox in your QuickTime Preferences.

For other, less common, media players and their plugins, see these websites:

• Shockwave
• RealPlayer
• VLC

Enable or activate plugins

If a plugin is disabled in the Add-ons Manager, you won't be able to use it.

1. Click the menu button , click Add-ons and themes and select Plugins.
2. Review the list of plugins to see if any of them are disabled.
   • To enable a plugin, click on Never Activate and select either Ask to Activate or Always Activate in its drop-down menu.

If you see an Activate (name of plugin) icon on web pages, where the plugin content should be, you'll need to click on the icon to activate the plugin:

For more information, see Why do I have to click to activate plugins?.

Update your plugins

Check that you have the latest versions of all your plugins.

• Go to our Plugin Check page and follow the links to update any plugins that are out of date.

Allow Plugin Container in your Internet security program

Allow your Internet security software (including firewalls, antivirus programs, anti-spyware programs, and more) to trust plugin-container.exe also known as Plugin Container for Firefox. For detailed instructions, see Configure firewalls so that Firefox can access the Internet where in that case Firefox means Plugin Container for Firefox.

Disable a conflicting plugin

If you have more than one plugin installed that can handle the same media type, this can cause a conflict that prevents some embedded media from playing. You may be able to fix the issue by disabling one of the plugins.

1. Click the menu button , click Add-ons and themes and select Plugins.
2. In the list of plugins, select the plugin you wish to troubleshoot.
   • If you want to disable the plugin, select Never Activate in its drop-down menu.
   • If you want to re-enable the plugin, select Always Activate in its drop-down menu.

For example, you may need to disable the VLC plugin to play embedded QuickTime or Windows Media content. For more information about troubleshooting problems caused by plugins, see the Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems article.

Other solutions

Clear the cache

See How to clear the Firefox cache.

Disable interfering extensions or ad-blocking software

• Ad-blocking software, such as anti-banner filters of your Internet Security program, or extensions, such as Flashblock or Adblock Plus, can prevent audio or video content from playing. If the site works with ad-blocking disabled, you may want to add the site to your whitelist in your adblocker filter.
• Any Firefox extension can also block plugins. If the video or audio plays when you disable all extensions, then one of your extensions was causing the problem. For more information, see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.

Check some Firefox settings

• Verify that cookies are enabled in the Privacy panel in the OptionsPreferences window. Verify that the site is not blocked in the Cookie Exceptions list.
• Allow the website as an exception in the Firefox pop-up blocker. The "Block pop-up windows" option is found in the Content panel of the OptionsPreferences window.

Remove specific entries in the hosts file (advanced users)

If you use a hosts file, you can temporarily disable it by renaming it Xhosts. Or, you can edit the hosts file to remove specific entries such as ad.doubleclick.net that can cause videos on certain sites to fail (for more information, see this MozillaZine forum thread). To apply changes to your hosts file, you may need to flush the DNS cache by entering the command: ipconfig /flushdns in the Run dialog box on Windows.

Based on information from Video or audio does not play (mozillaZine KB)