Uploaded video missing in node preview page

In my content type, am using video upload field of version 6.x-4.2-alpha2.

For creating a new content, i have specified a video file in the upload field and when i pressed the node 'Preview' option the uploaded video was missing.

When i did a view source of the preview page, i found the following object code

<object width="352" height="288" codebase="http://www.apple.com/qtactivex/qtplugin.cab#version=7,3,0,0" classid="clsid:02BF25D5-8C17-4B23-BC80-D3488ABDDC6B">
  <param value="" name="src">
  <param value="true" name="controller">
  <param value="tofit" name="scale">
  <param value="false" name="autoplay">
  <param value="http://www.apple.com/quicktime/download/" name="pluginurl">
  <embed width="352" height="288" controller="true" autostart="false" pluginspage="http://www.apple.com/quicktime/download/" type="video/quicktime" src="">
</object>

Here i have noticed that the source('src') attribute is missing.
Is it a problem with this version 6.x-4.2-alpha2. ?