First up, you need to clean your computer of anything 'flash'. To do that type these one by one in the terminal...
#!/bin/bash
sudo apt-get remove --purge flashplugin-installer
sudo apt-get remove --purge flashplugin-nonfree gnash gnash-common mozilla-plugin-gnash
sudo apt-get remove --purge iceweasel-flashplugin mozilla-flashplugin firefox-flashplugin
sudo apt-get remove --purge swfdec-mozilla libflashsupport nspluginwrapper iceape-flashplugin
sudo apt-get remove --purge xulrunner-flashplugin midbrowser-flashplugin xulrunner-addons-flashplugin
sudo rm -f ~/.mozilla/plugins/*flash*
sudo rm -f /usr/lib/firefox-addons/plugins/*flash*
sudo rm -f /usr/lib/firefox/plugins/*flash*
sudo rm -f /usr/lib/iceape/plugins/flashplugin-alternative.so
sudo rm -f /usr/lib/iceweasel/plugins/flashplugin-alternative.so
sudo rm -f /usr/lib/iceweasel/plugins/npwrapper.libflashplayer.so
sudo rm -f /usr/lib/midbrowser/plugins/flashplugin-alternative.so
sudo rm -f /usr/lib/mozilla/plugins/*flash*
sudo rm -f /usr/lib/xulrunner-addons/plugins/flashplugin-alternative.so
sudo rm -f /usr/lib/xulrunner/plugins/flashplugin-alternative.so
sudo rm -f /var/lib/flashplugin-nonfree/npwrapper.libflashplayer.so
(Source - Ubuntuforums)
And then install the 64 bit build of flash as directed here.
The instructions are pretty simple and easy to follow. So get the latest flash installed.
