Having problem while showing video on Windows XP

Question

I have created a web application; where user can upload video and also watch them.
This application successfully runs on Windows 7 OS; ie any browser can play video from win7 OS. But when i am trying to run the same apps on Win XP browser it is not played.

Plugins are automatically downloaded at Win7 browser but having problem with Win XP.
I am using Windows media player plugin to run video on browser.

Can anyone suggest me to get out of this problem.
Thanks in advance.

Thanks & Regards