No dice I'm afraid, BD. The Div-X installed QT behaved just as before,while MPlayer gave this error :
2012-02-07 22:01:57.876 MPlayer OSX[1287] Path to MPlayer: /Applications/MPlayer OSX.app/Contents/Resources/External_Binaries/mplayer_noaltivec.app/Contents/Mac OS/mplayer
2012-02-07 22:01:57.876 MPlayer OSX[1287] Arg: /Volumes/Music & Visuals/QuickTime video/The World At War/9 Stalingrad.mp4
2012-02-07 22:01:57.876 MPlayer OSX[1287] Arg: -framedrop
2012-02-07 22:01:57.877 MPlayer OSX[1287] Arg: -vo
2012-02-07 22:01:57.877 MPlayer OSX[1287] Arg: macosx:shared_buffer
2012-02-07 22:01:57.877 MPlayer OSX[1287] Arg: -slave
2012-02-07 22:01:57.877 MPlayer OSX[1287] Arg: -identify
dyld: Library not loaded: /usr/X11/lib/libfreetype.6.dylib
Referenced from: /Applications/MPlayer OSX.app/Contents/Resources/External_Binaries/mplayer_noaltivec.app/Contents/Mac OS/mplayer
Reason: image not found
2012-02-07 22:01:58.624 MPlayer OSX[1287] Abnormal playback error. mplayer returned error code: 5
Something to do with no Altivec?