Double clicking the file only works when the file is inserted with "store a reference" enabled. When that option is used, no file is actually inserted into the container field, only a filepath to the file's original location.
When you do this on the Mac, the file path stored in the container field is no longer a valid file path to that file and FileMaker cannot find that file in order to open it in QuickTime.
All I received from my friend was the FileMaker file. There were no supplemental .MP3 files that came along with the FMP file. Again, accessing the container field that contains the sound for each record works on the Windows 7, FMP 12 copy of the database, but not on the Mac running 10.9.3 and FMP 13.
To repeat, double clicking only works in FileMaker 12 or 13 when the file was inserted using "store a reference". This action tells FileMaker to find the original file and open it with the system's specified default application for that file type. It cannot open embedded files as they must first be exported before opening. So it would appear that you didn't get the file as well as the database.
Are you sure that this data was not inserted using FileMaker 11 in windows? There was an option that used OLE (object linking and embedding) that would embed a file and which could be opened via double click and this would not work with Macs. But this feature is not supported in FileMaker 12 and 13 so I do not see any way that a double click on a container could open any file. (A single click could run a script that exported and opened the file.)