If you’re importing from an AVCHD DVD camcorder, make sure your computer has the latest version of Mac OS X installed. If you’re importing from an AVCHD camcorder, make sure you’re using a Mac with an Intel Core Duo processor or better. If you’re importing video from a camera or other flash memory device, make sure the file format of your video is MPEG-2 or MPEG-4, which are compatible with iMovie. If you’re connecting to a device that records to flash memory, hard disk drive (HDD), or DVD media, you should be using a USB cable, not a FireWire cable.
If you’re connecting a tape-based camcorder to your computer, you should be using a FireWire cable (also called IEEE 1394, or i.LINK), not a USB cable. On some camcorders you must set the output to DV mode or HDV mode, depending on whether the content is standard (DV) or high definition (HDV). On some camcorders, this is called VTR or VCR mode, but not all camcorders use the same terminology, so check the documentation that came with your device. Your camcorder must be set to the correct output mode.
Your camcorder must be connected properly to your computer. For a list of compatible camcorders, go to the following support page: Your camcorder must be compatible with iMovie. Make sure that you’re using the correct equipment configuration: