That looks like you are trying to run it on xlsx files. This tool only works for the old binary (.xls) files, not the newer xml-based ones.
They are in the code: https://sourceforge.net/p/officeddt/code/HEAD/tree/trunk/testfiles/
Does not spot transcluded images in my test files
labels: images, defect --> images, defect, word, powerpoint
added test cases from bug #3
status: open --> accepted
as of r22, it finds the referenced file in the PPT. still working on the DOC...
now searches for Escher record links. Now finds...