I know this topic is old, but it seems like a useful place to leave breadcrumbs.
With Audacity and Avidemux it's pretty easy to sync and trim, and in many cases this can be accomplished without transcoding (decompressing and recompressing the video).
Install Audacity and add the FFmpeg libraries (along with the LAME extension).
Install Avidemux.
Open both the audio and video files in Audacity. The video will not be displayed.
In all the following operations, do not change the length of the video file, don't add or subtract from it.
Move the audio file until it is aligned with the camera audio.
Trim the file, or add silence, until the audio file is exactly as long as the camera audio.
Export the audio file to a new WAV file.
Open the video in Avidemux.
Go to the Audio menu, select track, use the drop down to Add Audio Track
Select the WAV created above.
Set Audio and Video Codecs to COPY
Select a MUXer - AVI is probably the most flexible.
Save the file, give it a location and name, append the correct extension.
Fran