I've got the same problem with a similar Samsung HMX-H100. The problem is with the metadata inside the movie file and it can be fixed without re-encoding (see a similar question).
I've installed mp4box (which is a part of the gpac project) using Homebrew: brew install gpac
Then I've managed to fix aspect ratios of my movie clips (I shoot in 720p) with the for x in *.MP4; do mp4box $x -par 1=1:1; done
command. Mp4box does the conversion in place so it's very convenient.