I wonder why doesn't your Yahoo! News item work on my Safari browser! Clicking on a video news item does indeed open a new window with a list of other news items on the bottom and a little description of the news item on the right side. However, there is no video! Also, I didn't find any indication that my browser lacks a plugin or something and I should install it to view the news item.
If one looks around on the page, there is a Settings button on the top, so I went there hoping to get things sorted out by changing some settings. The settings page tells me that Yahoo! already has selected a media player (none as far as I can see) and a connection speed too (no indicator as to what is the present setting). A user cannot select a media player if it is not in the list, and selecting the speed without the media player is kind of redundant. Oh and when you click on the Help link on the page, it takes the user to a generic Yahoo! Help page. Why couldn't you have put a link which went straight to information about video news items on Yahoo! News?
So, Yahoo! please fix your news media player application so that Mac users can also enjoy the content on Yahoo! News.