iMovie: MPEG artifacts or blank video bands in footage

If you're importing footage from your camera and you see see large blocks of MPEG artifacts or blank bands of video interspersed in the footage, the tape may be damaged or your camera may need cleaning. Consult the documentation that came with your camera to see if there is a way to clean the camera heads using a cleaning tape or similar procedure.

If you are using a camera that can record in multiple formats (such as HDV, DV, and/or DV Widescreen) and you see similar symptoms, you may have footage on the tape that was shot in different formats from multiple recording sessions. Avoid capturing different video formats on the same tape. Try using a fresh tape and record in one format to troubleshoot the issue.