An application that uses the WMV codec cannot play back content that is encoded in the MBR format
On a computer that is running Windows Vista or Windows XP with Windows Media Player 11, an application that uses the Windows Media Video (WMV) codec cannot play back content that is encoded in the Multiple Bit Rate (MBR) format.
This issue occurs if the content has protection from the Windows Media Digital Rights Management (WMDRM) and is encoded in the Multiple Bit Rate (MBR) format. When the MBR content is played back, only the sound is played. However, no image is displayed.
Note: This issue also occurs in Windows Server 2008.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB973442.