Ah, you got me there.
Only other thing I can think of is that win32 codecs installing to /usr/lib instead of /usr/lib64 on a 64bit (amd64, x86_64) system.
I use kaffeine to play vids most of the time and It uses the xine engine too. I do configure it myself, dvdcss, real-codecs, quicktime, and win32 codecs.. usually, the player picks up the dvdcss and win32-codecs and quicktime, but the real-codecs I have to tell it where they are.
Also, you can change the output mode used, (like vesa, opengl, etc,) by the xine engine, maybe that might be it.
see how you go, Glenn