If you want to edit your self-recorded video, any more compression than the already compressed DV codec will not be really suitable.
The DV codec takes 220MB/min which is only 125KB per frame (with 29.97fps) on a picture of 640x480 pixel (307200 pixel) which is less than half a byte per pixel (0.41B per pixel).
So that's what you have to live with. If you don't want to edit the videos, you can always convert them to something more compressed via iMovie or even Photo Booth