If you are doing Windows Presentation Foundation programming on your M400 and none of your Video's are playing it is very likely being caused by the Intel(R) Calistoga Graphics Controller....Disabling the driver (and forcing the computer to use the Standard VGA driver) will allow your video's to work - unfortunately it will also disable Aero.....

If you haven't played with putting video into a control yet it is a piece of case just requiring one line of XAML:

<Button Name="Button1" Height="60">

<MediaElement Source="c:\pain.wmv" Height="45"/>

</Button>