Premiere will work with so

Premiere will work with some MP4 files, problem is they are all not the same just like AVI and MPEG.

There are probably 20 different types of files with a .AVI extension, all very different in actual structure, same goes for the many flavors of MPEG.

You can try converting the files with Quicktime Pro $30, you can convert them to DV-AVI and those will work just fine.

If you are going to work with that camera and file format I recommend you do move to FCP, it will make your life a lot easier 😉