<video> src Problem

[oylesine]

Hello,
I am trying to create a video player with <video> HTML5.
My source is determined dynamically by javascript.
It works perfectly if I use a web link for src like:

document.getElementById("my_video").src=http://html5demos.com/assets/dizzy.ogv;

But I need to play a file on my localhost and following line is not working :

document.getElementById("my_video").src=http://localhost:7000/Videos/dizzy.ogv ;

There is just a gray box with X on it and when I click play the video, It gives me a popup window for downloading the video to pc.

What can be the problem ? I don't seem to understand
Please I need a quick help.
Thanks

[zcorpan]

does your local web server serve your video file with the mime type video/ogg?