If you are using version 3.5 of Auf geht's! for Mac and you encounter a script error in section 5.1.2 on screens B, C, or D, the media file used in this section may have gotten corrupted. To fix the problem, you just need to swap in a new, uncorrupted version of the media file.
Quit Auf Gehts and then go to the following location on your computer: Applications > Auf Gehts 3.5 > Part 1 > Audio
Download the zip file attached to this FAQ page, uncompress it, and drag it into the Audio folder. Make sure it is named Mundry Nort.mov with no changes from that name; that's how the program recognizes the file to access. When you drag it into the folder, you will see a pop up that says, "An older item named 'Mundry Nort.mov' already exists in this location. Do you want to replace it with the newer one you're moving?" Click the "Replace" button.
Once you have done this, launch Auf Gehts again, and this should resolve the error.