That is because you are still on 6.1 and 7.2 has a significantly changed interface for exporting file types. Dave was referring to the export options in the current version.
However, you can export a program stream (either mpeg1 or 2) from 6.1. There are options in that version to export as Program Stream 1 or Program Stream 2. I can't really help you beyond that as I have not had that version loaded for years and don't remember exactly how it worked. Check the PDF manual.