Difficulty seeing imported video files in iMovie

When you import clips from your camera they may appear instantly in your Browser but they are not fully imported. They take quite a while to be copied to iMovie.

If you remove the camera or SD card at that moment you will find that they have not been imported.

You can see the state of the import process by watching the pie-chart (arrowed). The white section shows that less than half the media has been captured.

You must only disconnect the camera when the whole chart is white. It can take many minutes to capture the contents of a card . . . depending on its size.