And where did you happen to acquire this file from since afaik there's no flashable version of MF2 floating around out there. MF2 is what was installed on most GS4A's from the factory which then upgraded to MF3 by OTA (again, afaik).
An MD5 "file" is just a very tiny text file with a line of info, usually the MD5 checksum and then the name of the file that checksum is associated with - we're talking about a file that's less than 100 bytes in size most of the time whereas the actual ROM file would end up being several hundred to at least 1.1-1.3GB in size.
Are you sure you understand what it is you might have downloaded?
