When I connect my digital video camera to my Mac, iMovie is not able to access it or iMovie can't control it.
If you don't see the "Camera Connected" message when you have your digital video camera connected to your Mac while iMovie is open, iMovie is unable to communicate with your camera for some reason.
Check the FireWire cable to make sure that it is plugged in properly. Make sure that your camera is turned on and in the output mode.
If these steps don't help, make sure that your camera is on Apple's iMovie compatibility list (see www.apple.com/imovie/compatibility.html). If it is on the list, there might be a problem with the FireWire port on your Mac; try another device in the port if you can. If your camera is not iMovie-compatible, you might need to try a different DV application.
When I'm editing my movie, the disk gauge turns red.
This means that the volume on which you have stored your iMovie project is getting full and you need to clear more space on the volume on which you are working. Try the following actions to get more working room:
Delete unused clips from the Shelf.
Select clips to which you have applied special effects and click the Commit button.
Empty the iMovie Trash.
Using the Finder, move files off the volume on which your project is stored.
Move the iMovie project to another volume that has more space.