A guy passing through gave me a DVD with an mdf and an mds file on it (each is a file with the same name, but one has the suffix mdf, the other the suffix mds. It's a movie he made. I can't watch the dratted thing. A PC-using friend said to use something called ISObuster to convert it to an ISO file (I think) - is there a Mac equivalent? What should I do with these files in order to be able to watch them, please?