Ubuntu – 2016: Firefox Replacement for Adobe Flash

For alternatives as you said, there's Gnash and Lightspark.

To install open Terminal (Press Ctrl+Alt+T) and copy the following commands in the Terminal:

For "Official PPA of the Lightspark project":

sudo add-apt-repository ppa:sparkers/ppa

or for "Automated daily builds from ustream git master":

sudo add-apt-repository ppa:sparkers/daily

Installation:

sudo apt-get update
sudo apt-get install lightspark browser-plugin-lightspark

Click here for instructions on using PPAs.

NOTE - Update for Ubuntu 15.04, using Lightspark Version 0.7.2-6 (The above PPA repository does not appear to be working in Ubuntu 15.04)

Lightspark 0.7.2-6 deb package can be installed directly via the software centre, which is invoked by clicking the "Install Using Apt" button on the following web page:

http://www.ubuntuupdates.org/package/core/vivid/universe/base/browser-plugin-lightspark

Well, basically if we want to keep up with Flash Player future versions and corresponding features and improvements, other than security fixes, we will have to switch to Google Chrome. Adobe went on to say that future updates to Flash Player beyond version 11.2 for Linux will be available only through the Pepper API that will run on Google Chrome and not through a download from Adobe directly. Mozilla hasn't provided any statement about this that I know of so far, so it is expected that Firefox will just use the last version provided by Adobe for the years to come.

I also wish that html5 takes over the Internet, however some functionalities still rely strongly upon Flash player, such as media streams and it will take some time until we get rid of it.

Read this and this for additional details:

There has been some heavy discussion about this as well at Ubuntu Forums. Check those out: 1 2 3