The software is seen as a video editor that has the capability of creating professionally good looking movies from various video clips. I don't think you can use it to dub the language. You would have to completely remove the audio stream that is already embedded in a movie file.
I would rather use the subtitles approach as it's more conveniently. This way you will keep the original audio file and provide subtitles under the video.
You can create subtitles with the help of Subtitle Workshop: http://subtitle-workshop.software.informer.com/
