Ubuntu 14.04: Flash plugin install using the tar file

Download tar file

wget -c http://get.adobe.com/flashplayer/install_flash_player_11_linux.x86_64.tar.gz

Install

mkdir /tmp/flashplayer
tar xvfz install_flash_player_11_linux.x86_64.tar.gz -C /tmp/flashplayer

cp -r /tmp/flashplayer/usr/* /usr/
cp /tmp/flashplayer/libflashplayer.so /usr/lib/mozilla/plugins/

To check, open firefox and type
about:plugins