How To Install Flash 10 in Portable Apps Firefox
The Portable Apps version of Firefox does not provide native Flash support. In prior versions of flash, there was a workaround. This has long ago stopped working. Here's a fix that worked for me. Copy a Flash 10 plugin DLL from an existing install into the Firefox Portable Apps version.In this case it's installed on my machine at the following location. The linked file is my own, provided for convenience.
C:\Common Files\Adobe AIR\Versions\1.0\Resources\npswf32.dll
Copy it into your Portable Apps Firefox directory here: