Linux x86_64 and FLASH

Fedora includes swfdec and gnash , which are free and open source implementations of Flash. We encourage you to try either or them before seeking out Adobe's proprietary Flash plugin software.
Users of Fedora x86_64 must install the nspluginwrapper.i386 package to enable the 32-bit Adobe Flash plugin in x86_64 Firefox and the pulseaudio-libs.i386 package to enable sound from the plugin.

• Create the 32bit mozilla plugin directory:

su -c "mkdir -p /usr/lib/mozilla/plugins"

• Install the nspluginwrapper.i386 , nspluginwrapper.x86_64 , and pulseaudio-libs.i386 packages:

su -c "yum install nspluginwrapper.{i386,x86_64} pulseaudio-libs.i386"

• Install flash-plugin as shown above.

         Run mozilla-plugin-config to register the flash plugin:

su -c "mozilla-plugin-config -i -g -v"

• Close all Firefox windows, and then relaunch Firefox.

        Type about:plugins in the URL bar to ensure the plugin is loaded.

Source