Sorry to ask yet another question, but I think I've almost got it all sorted!
I've just added a Sparkol music track to my video and it plays fine, but it doesn't start until a few seconds after the beginning of the video. I wondered if that has something to do with the animation at the beginning?
Also, the video is 2 minutes 9.5 seconds long so I chose a suitable track nearest to that length, which was 2m 13s, however the track not only starts late but finishes a whisker before the end of the video.
Any ideas please?