Ever since XP times powerusers have learned to try to keep the installed codecs up to date.
I personally used the k-lite codec pack for fresh system installs.
Ever since Windows 7 it seems like things have changed in the codec world. I don't remember if I had any trouble viewing video files without a codec installation.
This question basically answers some part of my question: Is there still need for codecs in Windows 7?
Now have things changed in Windows 8 with respect to DivX embedded support?