Problem Defragging in XP

My HD is becoming increasingly defragmented and I don't know how to fix the problem.

The problem is that disk defragmenter will not defragment certain files. The majority of them are TV shows or other mpg files (animatrix, various anime). The only non movie file that won't defragment is war3.MPQ. I'm really not sure why, its not even all the movie files.

Thanks in advance for any help.