It’s possible to clear your cache in Firefox with the click of a button, but if you need to find or clear a specific Flash file, you need to get under the hood. While the location of Firefox’s cached files can vary by installation, it’s possible to list them all by typing a command in the browser’s address bar.
Browser Caches Explained
When you go to a Web page Firefox will temporarily store portions of it locally on your computer. When the page is accessed later, the local copies of the page are reused and updated with any new content detected. This speeds page loading times and creates a faster browsing experience.
Firefox Cache Location
To locate cached Flash files or any other cached files in Firefox, type “about:cache” (without quotes here and in subsequent entries) into the address bar of the browser, and then press “Enter.” The Cache Directory item in the "Offline Cache Device" section shows you the path to the cached files on your computer. Under the "Disk Cache Device" section, click “List Cache Entries.” Search the listings for SWF and FLV file types to locate Flash files. To speed up searching, press "Ctrl-F" and type in common Flash file extensions like "FLV" or "SWF" to immediately find files with those extensions. To get more information, click the file link in the list. From there you can click the link next to Key to view the file itself.