Enable backports by adding the following line to your /etc/apt/sources.list file

deb www.backports.org/debian lenny-backports main contrib non-free

Import the key from the backports.org archive

apt-get install debian-backports-keyring

Run apt-get update

apt-get update

Install the Adobe Flash Player with one of the following commands depending on whether you like to use apt or aptitude

apt-get -t lenny-backports install flashplugin-nonfree

aptitude -t lenny-backports install flashplugin-nonfree

Restart your web browser and then test your Adobe Flash installation by watching a a flash movie. You should notice that the Adobe Flash Player has been installed on your Debian Linux system.

<object height="344" width="425"><param name="movie" value="http://www.youtube.com/v/oHg5SJYRHA0&amp;hl=en&amp;fs=1&amp;" /><param name="allowFullScreen" value="true" /><param name="allowscriptaccess" value="always" /><embed src="http://www.youtube.com/v/oHg5SJYRHA0&amp;hl=en&amp;fs=1&amp;" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" height="344" width="425"></embed></object>