I’ve found that viewing flash sites with the older 7.x version of the flash-plugin RPM from macromedia.mplug.org was becoming problematic. Slowly but surely sites with flash that I have been frequenting appear to have stopped working correctly, or have experienced choppy performance, with this version of the flash-plugin.
Just visit the flash download page and choose the Installer for Linux, not the stand alone player.
As of the time of this post the latest was FP9_plugin_beta_112006.tar.gz
Simply unpack using: tar -zxvf FP9_plugin_beta_112006.tar.gz and copy the file to your mozilla plugin directory, which on Fedora Core 6 is /usr/lib/mozilla/plugins, by typing these commands cd flash-player-plugin-22.214.171.124 followed by cp libflashplayer.so /usr/lib/mozilla/plugins.
Now simply restart Firefox and you are all set. I’ve noticed flash video appears better and doesn’t looase sync with audio anymore.