Solution
Using the supplied software Data Import Utility to save your movies, you have the additional advantage of automatically joining scenes that were saved as multiple files so you can work with them as single scenes with the editing software of your choice.
The following types of scenes can be joined:
Multiple video stream files of a single scene (either AVCHD or MP4 format) split because of the 4 GB maximum file size restriction.
Relay scenes (either AVCHD or MP4 format) that were saved on separate memory cards.
Data Import Utility cannot be used to join image files imported into the computer. To join multiple files in the computer, use commercially available software equipped with editing capabilities for the desired file type.