Take a look at this tidbit I found here
"In order to use the flashplayer plugin with Mozilla in Fedora Core 1, Install the package "compat-libstdc++" via 'apt-get install compat-libstdc++' (if you have apt ofcourse) or from the Fedora Core 1 installation CD3. Then make sure you have libflashplayer.so and flashplayer.xpt in the correct mozilla directory." - copied from Fedoranews.org
There's always the Mozilla plug-in FAQ
, but you mave have been there already.
Good luck and I hope this helps,