Adobe flash player 64-bit on Linux
1. Download Adobe Flash Player 64-bit from http://labs.adobe.com/downloads/flashplayer10_64bit.html . Unpack the file. You will get libflashplayer.so.
2. Remove existing version of flash player(s)
sudo apt-get remove -y --purge flashplugin-nonfree mozilla-plugin-gnash
sudo apt-get remove -y --purge swfdec-mozilla libflashsupport nspluginwrapper
3. Copy and link the plugin to browser(s) directories
sudo cp libflashplayer.so /usr/lib/mozilla/plugins/
sudo ln -sf /usr/lib/mozilla/plugins/libflashplayer.so /usr/lib/xulrunner-addons/plugins/