ALL miniDV camcorders use Firewire to transfer DV video.
NO miniDV camcorders use USB to transfer DV video. Not one.
Many miniDV camcorders have USB ports, and these are for transferring still images.
Many camcorders can also use USB to stream video, whether live or from tape playback, but these are at a lower resolution like 320x240 or 640x480, and they stream in some format other than DV. Basically the camcorder is acting as a webcam. You CAN capture video for editing this way, but you will not be getting the full quality of the DV format - it will be lower resolution, possibly have jerky or skipped frames, no timecode data, and no software deck control.