Rich is correct, the clips can be stitched together in the iMovie timeline.
You may already be aware that when DV tape is imported into iMovie you see a collection of multiple clips.
These individual clips coincide with the record start and stop points on the camcorder, these are called scene breaks, and are identified in iMovie by the timecode on the tape.
If you record for, say , 3 seconds, the imported clip will be 3 seconds.
If your very short clips do not coincide with start and stop points then this may be due to some other reason, such as dirty heads in the cam'.
So if the recording has had multiple start and stop points, then multiple clips will be imported.