The zip file Card04.zip will decompress into a directory CARD04 that has a CONTENTS folder. Inside that folder are these subfolders:
AUDIO and VIDEO are what's important, and the latter is where it stored 15 seconds of video in >50MB.
Some research warns that changing the file names or directory structure will ruin everything. There are lots of programs out there that will convert the individual MXF files, but I don't see anything that will overlay the audio onto the video in synch, and spending several hundred more dollars on APP is unpleasant. (Although if we're unable to obtain a license through one of the non-profit corporations that would be using this, I may end up having to do it.)
Fortunately, several people including pcornelius have said they have a handle on programs that may be able to do this, but I'm putting this challenge out there so that anyone reading this who can help can try the solution you propose yourself and see if it works.