Searching and saving cache files is quite simple in Firefox and you have basically 2 ways.
Type about:cache in Firefox’s address bar and you will get back 3 different cache types that Firefox uses, namely Memory cache device, disk cache device and offline cache device. Click on the link that says “List Cache Entries” and you’ll see a list of all the files that are in each cache type. Unfortunately, there’s no obvious ways in this scenario to really save something FROM the cache. Most people will just click the link back to the original source of the file and have your browser download it all over again and that would be enough just to get what you want. But again, it seems that not all files are stored and can thus be saved from the cache anyway. If you’re really adventurous, look for files listed in the disk cache with the folder and filename listed in the property “file on disk”. These cache files can be saved by browsing to the cache folder and adding the appropriate file extension to it.
2) CacheViewer Firefox Extension
CacheViewer serves as a front end GUI interface to browse your memory and disk caches. The search function has proven to be handy and can help you filter and search for certain filetypes in your cache. For example, we know that most flash games ends with the extension .swf, so all we need to do in order to save that flash game that we were playing a few days ago is to type in swf in the CacheViewer search box, and a list of all the swf file in your cache will be returned.
Once you’ve found which file you want in the cache entries, just right click on it and “save as…”
That’s it. Enjoy. Any questions please leave a comment.