Yes, the extension don't work for some time for me, right now I have other things to fix, so I left out.
But flash can also install by hand.
-go here
http://get.adobe.com/flashplayer/-download a .tar.gz file for linux
-extract libflashplayer.so in /home/tc/.mozilla/plugins if you use firefox (for other browser I do not know the directory, but should work equally)
-start or restart firefox, flash works!
-backup you mydata to store flash