I just tried putting the beta tarball back into the unpackdir directory and re-running dpkg-reconfigure, and restarting FireFox. The problem didn't come back (I still only have the new r31 version of the plugin showing up in about:plugins).
BTW, info about moving the unpackdir directory should be made to bug #80545: https://bugs.launchpad.net/ubuntu/+source/flashplugin-nonfree/+bug/80545 as that's where it was originally reported. -- Upgrade of flashplugin-nonfree doesn't remove the old version https://launchpad.net/bugs/81385 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
