Ubuntu 16.04, Firefox Youtube - perfect, everything goes well. EarthCam.com - doesn't work. It seems like stop downloading page at the moment of start downloading flash. Some other pages with flashes also don't work.
If Flash doesn't work, simply run this command in Terminal.
Type in your password (if prompted).
Then, type in the following command:
apt-get install flashplugin-installer
Hopefully you should be able to take it from there! Enjoy flash!
By the way, this is Flash Player 11.2 - Further versions will not work with Linux.