Hi Customer (name blocked for privacy),
If you right click on the movie that you are trying to play, it should give you a pop-up menu with an option to save the movie file to your hard drive.
Does that work at all? If it does, that might at least confirm that the object that you are attempting to view has valid links associated with it.
If not, rather than your PC's configuration having a problem, it might be that Yahoo has a problem, or the object that is supposed to be a movie file might have a bad link. That is likely the case if you have no problems running video media from other sites on your browser.
If you are able to provide the link or other info, I'd be happy to try playing the movie from my PC. If it doesn't work for me either, then you probably don't have a problem - it would be Yahoo's problem in that case.
Anyway, let me know your thoughts.
Regards,
BusyBee.