You are rather consequent in referring to v.851.
Are you sure that you don't mean version 1.00 RC1 build 805?
(Though the problem referred to in the linked thread concerned build 803, it hasn't changed for build 805.)
Further: are you sure its DivX decoder you're using? Though it indeed cannot be accessed though Options > Preferences > Video, you should be able to reacht it (with movie loaded) through Options > Filters.
If it appears you're perhaps using ffdshow; perhaps it's an older version?
http://sourceforge.net/project/showf...group_id=53761