How to Play AVI Files on Firefox

By Mike Benson

Because of the magnitude of available codecs, AVI files can come in a variety of types. Although some of the more common AVI files such as DIVX will usually play in an embedded DIVX player, others may automatically download to your computer instead. You may have noticed that this problem sometimes occurs on Mozilla Firefox when it does not on Microsoft Internet Explorer. As long as you have the proper codec necessary to play the AVI file, you can also play it in Firefox using Windows Media Player. This is extremely useful for large AVI files, as you do not have to wait until they have finished downloading to watch them. Achieve this by modifying the Firefox plug-in file to recognize and play AVI files in Windows Media Player.

Step 1

Close Mozilla Firefox. Open a Run dialog by simultaneously pressing the "Windows" and "R" keyboard keys.

Step 2

Type "C:\Users" and press the "Enter" key. This opens a new window containing user folders on your screen.

Step 3

Double-click your user folder to open the directory. Click "Organize" located at the top, and click "Folder and Search Options." This opens a Folder Options window on the screen.

Step 4

Click the "View" tab, and click in the radio button next to "Show Hidden Files, Folders, and Drives" located under the "Hidden Files and Folders" section in the "Advanced Settings" area. Click the "Apply," and "OK" buttons to save and close. This action causes Windows to display more folders inside your user folder.

Step 5

Double-click to open the "AppData" folder. This takes you to a new directory containing three folders. Click the "Roaming" folder. The Roaming folder contains a large list of folders belonging to various programs installed on your computer. Locate and double-click the "Mozilla" folder. Once in the Mozilla directory, double-click the "Firefox" folder.

Step 6

Double-click the "Profiles" folder located in the "Firefox" directory. This will display a folder having an alphanumeric name followed by the word default. Double-click to open this folder. Inside this directory are all the configuration settings applicable to your Mozilla Firefox profile.

Step 7

Double-check that Mozilla Firefox is closed before proceeding. Locate and right-click the "Pluginreg" file and click "Open With." This opens an "Open With" dialog. Click to highlight "WordPad," and click the "OK" button at the bottom. This opens the "Pluginreg" file in WordPad.

Step 8

Press the "Ctrl" and "F" keyboard keys simultaneously. This opens a Find dialog. Type "Windows Media Player," and press "Enter." This takes you to the Windows Media Player section in the Pluginreg file. By default, the section will look similar or identical to this:Microsoft® Windows Media Player Firefox Plugin|$100|application/x-ms-wmp|np-mswmp|*|$1|application/asx||*|$2|video/x-ms-asf-plugin||*|$3|application/x-mplayer2||*|$4|video/x-ms-asf||asf,asx,*|$5|video/x-ms-wm||wm,*|$6|audio/x-ms-wma||wma,*|$7|audio/x-ms-wax||wax,*|$8|video/x-ms-wmv||wmv,*|$9|video/x-ms-wvx||wvx,*|$

Step 9

Locate the number listed directly below the word Microsoft. In the example above, the number is 10. Add one to the number. In this example, you would change the number to 11.

Step 10

Look at the last number in the section. In the example above, the number is 9. Add one to the number. In this example, you would change the number to 10.

Step 11

Add "|video/x-msvideo|Media Files|avi,*|$" (without the quotes) to the line. In the example, the section would now look like this:Microsoft® Windows Media Player Firefox Plugin|$110|application/x-ms-wmp|np-mswmp|*|$1|application/asx||*|$2|video/x-ms-asf-plugin||*|$3|application/x-mplayer2||*|$4|video/x-ms-asf||asf,asx,*|$5|video/x-ms-wm||wm,*|$6|audio/x-ms-wma||wma,*|$7|audio/x-ms-wax||wax,*|$8|video/x-ms-wmv||wmv,*|$9|video/x-ms-wvx||wvx,*|$10|video/x-msvideo|Media Files|avi,*|$

Step 12

Press the "Ctrl" and "S" keyboard keys simultaneously to save the changes, and then close WordPad.

Step 13

Open Mozilla Firefox, and click on an "AVI" file. Instead of downloading, the video will now automatically begin playing inside of Firefox.

Tips & Warnings

  • Firefox must be closed while modifying the Pluginreg file.
  • In the event you ever want to download the AVI to your computer, right-click the link and click "Save As" to proceed with downloading.