If you have problems with Flash 10 in Firefox for Ubuntu .
Because of some conflicts you need to unistall the following packages and then install the only one you need : flashplugin-nonfree.
kartook@.-:~$sudo apt-get remove swfdec-mozilla
kartook@.-:~$sudo apt-get remove mozilla-plugin-gnash
kartook@.-:~$sudo apt-get remove adobe-flashplugin
kartook@.-:~$sudo apt-get remove flashplugin-nonfree
sudo apt-get install flashplugin-nonfree
That’s it.Easy to use and a must do.