To install the Flash Player plug-in for Firefox on Debian Linux is really so easy. Its a matter of running aptitude install as root user.
Here's how to.
Ensure you have the non-free repositories added to your apt-get sources list.
# cat /etc/apt/sources.list
# Debian Main Repository
deb http://ftp.uk.debian.org/debian/ wheezy main contrib non-free
deb-src http://ftp.uk.debian.org/debian/ wheezy main contrib non-free
I run wheezy, which is the current testing release
Notice I added 'contrib non-free' to the repository.
First run a search to find the Flash Player Plug-in and get the name:
# aptitude search flashplugin
p flashplugin-nonfree - Adobe Flash Player - browser plugin
Now aptitude will install:
# aptitude install flashplugin-nonfree
Launch Firefox/Iceweasel. If its already running, then close and restart.