Comment 132 for bug 2697

Marcelo, the bug is fixed. If there's a problem for you, it's most likely that the 64bit Linux installs which use a 32bit plugin wrapper for Flash are not whitelisted yet.

That smells strongly of a separate bug. It may already exist, and it may really belong with Kubuntu/Ubuntu (which have packaged the flash plugin as such.) If it's Mozilla's territory, and there's no bug yet, then you should probably file a new one depending on this or some such.

In any case, trying to determine how to use the about:config prefs for this is definitely support, so seems like that belongs where timeless said.

-[Unknown]