It appears to me that 'dvdauthor.tcz' was originally build against an older version of 'ImageMagick.tcz'. The current extension contains 'libMagickCore.so.4'. So the proper way to resolve it would be to re-build 'dvdauthor.tcz'.
OTOH you could try to "cheat": cd /usr/local/lib ; sudo ln -s libMagickCore.so.4 libMagickCore.so.2 ; sudo ldconfig
This might work or maybe not, but you could at least give it a try.