Step-by-step – Flash Plugin Installation in Debian Bullseye

Installing

2. 2. Setting Up Non-Free Repos

   Enable the Apt Contrib/Non-Free Repository Sources

   Enabling Debian Extra Repo

   Apt Contrib/Non-Free Setup

3. 3. Installing Flash Plugin

   Then to Install Flash Plugin for Debian
   Simply play:

   sudo apt install pepperflashplugin-nonfree

   Authenticate with the User Admin Pass.
   If Got “User is Not in Sudoers file” then see: How to Enable sudo.

4. 4. Testing Flash Plugin

   Finally, to Check the Plugin is Correctly Installed
   On Firefox point to address:

   about:plugins

   On Opera:

   opera:plugins