Re:Watch boot video here. (Score 1)

DiskWarrior doesn't do 'defragging' of the hard drive. It rebuilds a feature of HFS disks called the 'directory' -- the listing of where files are on the disk. Analogous to defragging the disk's contents, but not the same thing at all. Yes, ever since Panther, files (under some conditions) are defragged on-the-fly.