If you want to test the latest beta of the Flash 9 Player then follow these steps. Note: There’s a newer beta out which can be found here. The directions below should still work.
1. Download the correct binary for linux at Adobe labs
http://labs.adobe.com/downloads/flashplayer9.html
2. Unpack the files into a directory somewhere.
tar -zxvf downloadedfilename.tar.gz
3. Copy libflashplayer.so into the following directory
sudo cp libflashplayer.so /usr/lib/mozilla/plugins/
4. Give the file correct permissions.
Code:
sudo chmod 644 /usr/lib/mozilla/plugins/libflashplayer.so
5. Link the file to Firefox’s plugins directory.
Code:
cd /usr/lib/firefox/plugins/
sudo ln -s /usr/lib/mozilla/plugins/libflashplayer.so libflashplayer.so
6. Restart Firefox and enjoy! You can put about:plugins in the url bar and hit enter and look for Flash Player 9 to make sure it’s installed.
If you’re having issues you can leave a comment here or on my thread over at Ubuntuforums.