MSWU-001 fails to download through Patch Remediation Center
There are two updates that comprise MSWU-001: one for WMP9 and one for WMP10. Even unchecking the update that fails to download does not allow the bulletin to download partially.
The location it's trying to download from: http://download.microsoft.com/download/8/c/b/8cb07a83-3b1c-4a95-a1c7-4e788c113829/windowsmedia9-kb892313-x86-intl.exe. The URL appears to be broken, even if you try to download the file yourself. So the problem is either on Microsoft's side for not providing a new download location or on SMP's side for not pointing to an updated download location that the PRC can use.