Probably a licensing-related limitation. Keep in mind that this kind of codec technology is often subject to license fees. So, for freebie products like "Silver" versions that are not time-limited, it stands to reason that the technology wouldn't be included.
I know that my mpg files aren't mpeg4 and they don't even show up in the Import dialog unless i choose "View all files".
If I try to open a file with the extension mpg, NOTHING happens.
If I rename it to .mpeg, i get an error msg saying I need to Activate the program to import this kind of MPEG files.
Yet there is no link anywhere in the menus to activate.
I thought normal mpeg 1 and 2 were free formats?
Something is buggy in this program.