None of these steps above worked for me. I got flash finally working in my Firefox on 12.04 (flash stopped working after I updated Firefox to latest version recently (December 2013)).
So, it case it helps anyone, I finally got flash working again by using an older version of adobe flash (10.3.183.75). I simply installed the libflashplayer.so file in
The file to download from
"(Released 4/9/2013) Flash Player 10.3.183.75 (61.21 MB)"
(others might work, I tried this one first and it worked so I didn't try any others).
Once you unzip the archive:
If there is a link already existing in /usr/lib/mozilla/plugins to a different libflashplayer.so then delete it first.
Then run these commands
tar -xzvf flashplayer_10_3r183_75_linux.tar.gz
sudo cp -p libflashplayer.so /usr/lib/mozilla/plugins/libflashplayer.so
And now my flash is working in Firefox for youtube videos, etc.