Archived - iMovie '09: Importing AVCHD clips from some multi-format camcorders may require additional steps
Some camcorders that record multiple formats require extra steps to import both formats into iMovie ’09. If you have recorded both AVCHD and MP4 (or iFrame) formats with certain camcorders, iMovie will only recognize the MP4/iFrame video clips in its 'Import' window.
To view and import AVCHD clips from your multi-format camcorder in iMovie, MP4/iFrame footage should be imported, preferably backed up, and then deleted from your camcorder. After all MP4/iFrame clips have been deleted from your camcorder, disconnect the camcorder from your computer and then reconnect it back again. The AVCHD clips should appear in the iMovie Import window.
iMovie '11 (version 9.0.1 and later) allows you to import from multiple formats using Camera Import.