Firefox Gnash plugin doesn't work

I have gnash and the gnash plugin for firefox (all for x86_64) loaded:
        $ rpm -qa 'gnash*'
        gnash-0.7.2-2.fc7
        gnash-plugin-0.7.2-2.fc7
Some flash sites seem to work (more or less), but not the videos on
google videos (ie. http://video.google.com/?tab=wv ), which (I suppose)
are in Flash format.  Gnash appears to be invoked, judging by the
message that appears by right clicking the box in which the video ought
to play, but nothing happens; the box just stays black.

Questions:

(1) Where from can I load an actual flash video file for testing gnash
itself?

(2) Does this gnash plugin work for others?

Thanks - jon