I have always have the issue that FireFox does not know which plug-in to use to play AVIs. Some of us have resorted to using QuickTime, but QuickTime does not fully support all the AVI compression formats. So sometimes, QuickTime it won't play the AVI. Well, I finally figured out how to fix this problem, because Windows Media Player has much better support for it I went with their plug-in.
First off you are going to open Windows Explorer, then you are going to explore to C:\Documents and Settings\(Your username)\Application Data\Mozilla\Firefox . Application data is a hidden folder, so you may have to go to Folder Options and turn on hidden files. In this directory we are only concerned with the pluginreg.dat file. Make a backup of this file before you go any further.
Double click the file to open it. The first window you will see is a warning....blah blah blah....click "Open With..."
Now a second window will pop up that asks what you want to do. Select "Select the program from a list" and then click "OK"
Choose WordPad as the program to open the file. Make sure that the "Always use the selected program to open this kind of file" button is NOT checked. Then click ok.
Once the file opens we are only concerned with the highlighted part of the text.
Replace the "9" with "10" . If their is a number other than 9 in this location, simply add one (1) to what ever number may be there. Below this you can see a numbered list of files types that are opened with the Media Player plug-in. At the bottom of the list insert this code "9|video/avi|Media Files|avi,*|$", again, if the numbers do now match the example simply add one to the last number in the list. Before you save this file, make sure that all windows of FireFox are closed...that includes this one. :) Once you save and start up Firefox again you should be all good! There is an AVI linked at the bottom of the page that is linked, if it loads when you get back, then you did good!
