I found two solutions to my problem but I don't really understand why one works and one does not.
Solution 1: I did something wrong because this resulted in a file of the audio track with no video. The audio was however in the correct language.
Solution 2: This seems to have worked perfectly.
ffmpeg -i source.avi \
-map 0:0 -map 0:2 \
-c:v copy \
-c:a:2 copy \
Could someone please explain my error with solution one?
mencoder -oac copy -ovc copy -aid 2 source.avi -o output.mpg
It seems odd that I would need to use mencoder instead of ffmpeg to specify which audio track the output should use.