Just recently I've started getting this error. I can download the vid and it will play, but not view it in Firefox anymore. It seems to have started after I installed Microsoft.NET Framework. In IE it works. In 'about: plugins' everything appears OK.
XP Pro, media Player 8 w/ WMP 9 encoder add ons.
XP Pro, media Player 8 w/ WMP 9 encoder add ons.