I recently imported some Mini DVs of videos I took over the past year and a half but because iPhoto/iMovie orders them by create date and time, which is the imported file and not when the video was recorded, my videos were out of place in my ordering of photos and videos. I needed to change the create date and time of file itself so they appear in the correct order.
The easiest method I found which allows batch changing of create and modify date and time is described on this site here http://danilo.ariadoss.com/howto-change-date-modified-date-created-mac/.
touch -mt 200801120000 path-to-folder/*