Video Shelf(sample project) - videos are not playing in Windows XP

[nasayoo]

I used one of the sample WPF project named as Video Shelf which was provided by Microsoft wih the Expression Blend 2.5. When I run that project in Windows Vista, the project is running without any errors and the videos are also playing.(running - tried both in Debug mode and after publishing). But when I run the same project in Windows XP, its running without any errors, but the videos are NOT playing i.e. the video shelf will display and when I click one video, the video is not playing and no exceptions were thorwn as well.
So why is this happening?

Thanks in advance

[kirupa]

When you attempt to open the individual videos using Windows Media Player, do they play?