Comment 10 for bug 250769

(In reply to comment #9)

The bug is being hit because newer versions of swfdec have windowless support.

https://bugs.launchpad.net/ubuntu/+source/firefox-3.0/+bug/239182

The macromedia plugin will hit the same bug when it has wmode support.

(I don't know how many users use use swfdec or gnash or the macromedia plugin [with nspluginwrapper for 64-bit].)