That’s Microsoft’s MPEG-4 version 2 codec. I think you can get it here
http://www.microsoft.com/windows/windowsmedia/format/codecdownload.aspx
(any of the 3 downloads work - the first requires you to have windows media player 7, the other 2 don’t)
or here
http://www.microsoft.com/downloads/details.aspx?FamilyID=73c47878-20d0-4c1a-96f4-177d7e0074b7&displaylang=en
