I'm certain the collective wisdon of YACF will have this one sorted swiftly. When I visit Youtube the screen all displays ok but the video's just show as a black rectangle, though I do get sound ok.
Any ideas what's up? It used to work ok so it might just be the current version of Firefox that's borked (3.6.13). Am currently downloading 3.6.15 to see if that fixes it. All other useful ideas welcome.