Comment 7 for bug 1165630

A deinstall is simple. Just go into synaptic and type in flashplugin. Completely uninstall any flashplugins that show as installed.

If you are only interested in using the older plugin on a per user basis rather than system wide the easy way to do it is to extract libflashplayer.so from the flashplugin package you want to use . Then go to the /home/'username'/.mozilla/firefox/'profile-name' folder. There should be a plugins folder under it. Insert libflashplayer.so in the plugins folder.

If the plugins folder does not exist, create one.

 /home/'username'/.mozilla/firefox/'profile-name'/plugins

When you restart firefox it should recognize your flashplugin.

As for Chrome. I am not getting it's newer flashplugin to work either.