Yeah, the mpeg2 files on my SONY HDD camera will only play back in VLC.
However, the files will import into iMovie 09 just fine directly from the camera.
Short answer, yes, you'll need the MPEG2 component with Quicktime Pro to edit these clips in Quicktime, BUT, you do not need either if you simply import the clips directly into iMovie 09 by connecting the Camera to your Macbook.
Here's a little something strange that I've noticed with my Sony camera. Mine's a High Definition camera that also shoots in standard definition.
-For HD it uses AVCHD in various 1080i resolutions depending on the quality settings. These files are completely unplayable on my Macbook when copied to my hard drive, but they work perfectly when imported through iMovie.
-For SD it uses MPEG2 at 720x480. These files are playable on my Macbook with VLC (free) and in Quicktime if I had the MPEG2 playback component (money). These files also work perfectly when imported through iMovie.
-Here's the tricky bit, if the camera has any SD footage on it at all, that is all that iMovie will see when you go to do an import. So if you have HD footage that you think just doesn't work with iMovie 09, just back up all of your SD stuff and remove it from the camera and then the HD stuff will show up in the import browser.
Oh, and iMovie 09 has a direct to youtube uploader.