Video notes:
Navigate in the registry to HKLM\Software\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background
Then see if there is a DWORD value called OEMBackground and if so set the Hex value to 1. If you do not have OEMBackground then you need to create a new DWORD value key called OEMBackground first.
After you are done navigate to c:\windows\system32\oobe\ and create a info folder and then inside it create a background folder and put a JPEG file in there that is less than 256KB and call the file name backgroundDefault.jpg , then reboot and your done!