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I have a new PC running Windows 7 and Office 2010. My default browser is Firefox. I also have a website that was produced entirely in-house and is hosted by (

On the site there are a few .AVI videos. For some reason Firefox will not play the videos and always says a plugin is needed - but all the video plugins are up to date. Interestingly if I open the website in Internet Explorer 8 the video plays fine. Can anyone help with an explanation?

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You do know that AVI is a video format created by Microsoft, right? So it is not surprising that IE can play it even if other browsers can not. – JohnFx Dec 27 '11 at 0:23

There has to be a plugin to play embedded avi files.

avi files can be codic in so many ways most likely you need divx ... since this seems to be the default stardard for most .avi files on the net.

for divx (you want the free release
Divx WebPlayer

I would like you to follow this SO thread: how to open avi file in firefox using Window media player

Now, if you want to use another player to play avi you could use those type :

video/avi (not sure about this one)
video/quicktime (not sure about this one)

More information on the WMP plugin and how to load it (via page source) in the Plugin Doc of Mozilla

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Thanks for the advice . I've downloaded and run the divx stuff but still no joy in firefox but fine in ie8 – the watchmaker Jan 2 '12 at 0:42

In order to play embedded AVI's and other Microsoft formats, I'm pretty sure you have to have the Windows Media Player plugin installed and enabled. Can you check and see if it is installed and enabled?

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You can use the K-Lite Codec pack for your version of Windows and it will install the necessary codecs required to run any format of video available.

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