Just a heads-up and/or query as to whether anyone else sees this.
It appears that since the latest updates to the Flashplugin the combination of the Nvidia173 driver (for FX5200) and firefox no longer works for most flash videos (YouTube & BBC News).
I don't see any problem with other browsers (e.g. Rekonq) or other X drivers (including Nouveau on the same machine).
Given that it looks to be an interaction of 2 pieces of non-free software there's probably not a lot of point submitting a bug (unless Adobe have a bug system, since it was their software that changed most recently).