For older videos which will not be remastered with music, you can always add your own music with a little post production by downloading the video file and then adding your own music using free software like LosslessCut to strip the video's audio track and then bring it into Audacity where you can add whatever music you would like to the video, and then export the file and again merge it back into the video with LosslessCut. You can mix the levels as you wish so any sound in the video, such as the model speaking would not be missed.
All of this is done without having to re-encode the video so it is quite easy and quick to do. Of course it is extra effort and may be more than you wish to do.
