sudo aptitude install flashplayer-mozillainstead.
Linux aficionados know that Adobe suspended further development of Flash for Linux. Only updates to version 11 will be provided through 2017.
Google Chrome does however continue to update and support a special embedded version of Flash called PepperFlash which is currently at version 16.
I just discovered that PepperFlash can be used with FireFox, albeit in a circumventual way.
"Fresh Player Plugin" is the PepperFlash wrapper for Firefox by i-rinat on github. I originally found this information on Web Upd8.
It was easy to install without issue. I found that my Debian distro had a pepperflash installer in it's repo; however, installing Google Chrome will work just as well.
sudo aptitude install pepperflashplugin-nonfree sudo update-pepperflashplugin-nonfree --install
Then I was able to install Fresh Player Plugin as per documentation:
sudo apt-get install cmake gcc g++ pkg-config ragel libasound2-dev libssl-dev libglib2.0-dev libpango1.0-dev libgl1-mesa-dev libevent-dev libgtk2.0-dev libxrandr-dev libxrender-dev libxcursor-dev libv4l-dev libgles2-mesa-dev libavcodec-dev libva-dev libvdpau-dev libdrm-dev libicu-dev #optional: sudo apt-get install libpulse-dev libjack-jackd2-dev libsoxr-dev
cd ~/Downloads #(or your preferred folder) git clone https://github.com/i-rinat/freshplayerplugin.git cd freshplayerplugin mkdir build cd build cmake -DCMAKE_BUILD_TYPE=RelWithDebInfo .. make cp libfreshwrapper-flashplayer.so ~/.mozilla/plugins/
Restart your firefox and take it for a test-run.
My FireFox reported the following using the Adobe About version check.
To make it easier to update, I've scripted the make/install process which can be run manually on occasion, or as cronjob. If the build ever fails, i've found it best to delete the folder freshplayerplugin and re-clone it.
cd ~/Downloads/freshplayerplugin/ git pull mkdir build cd build cmake -DCMAKE_BUILD_TYPE=RelWithDebInfo .. make && cp libfreshwrapper-flashplayer.so ~/.mozilla/plugins/ && firefox "https://www.adobe.com/software/flash/about/"&
As always, Good luck!