While Flash Player is a pretty vulnerable plugin, a lot of sites on the web require flash to function correctly. And for those of us with portable versions of FireFox, we might need it from time to time. But how to install it? Here’s how:
Visit FlashPlay to download the FireFox XPI. You can use this to install the plugin directly.
Alternatively, use 7-Zip to extract the Flash DLL file, and put it in the Data/Plugins folder of Portable FireFox.
If you don’t trust FlashPlay, then open the folder of a local Flash installation ( C:\Windows\system32\Macromedia\Flash\ ) to find the DLL file, as described by LifeHacker.