Good question. As a hobby, I like to rework a lot of old and new videos with audio and typically use what I feel complements the person and/or setting. I may leave parts or the entire original audio if something in it appeals to me and/or adds to the music I use. Sometimes I find myself dubbing a posing routine with both the original song and a song I think suits the movement and energy of the poser.
It all depends on how I feel at the moment. I may use Bossa Nova on one video, deep underground House music, Boards of Canada, Jamiroquai, or as of recent, Giorgio Moroder's - Midnight Express - Theme from Midnight Express (both vocal and Instrumental), which I used for a Inna Uit WPW video I reworked just for my personal taste.
It also depends on the type of music you like. If you have a broad interest in different forms of music, then I think it's a lot easier to pick and choose or have an ear for what fits the visual setting, according to your preference. The more you do it, the more you'll find yourself creating a style of your own.
Apart from recreating videos for personally amusement, I never dub interviews. I actually enjoy listening to what many of the women have to say just to get a feel for who they are as individuals. One of my favorite interviews is an old one with Laurie Fierstein. She's a brilliant and very open minded woman.
In the case of Jannell Ennis and women that do or did similar videos with a lot of talking, I prefer no audio. I love Jannell's personality, her voice, and how she asserts herself when talking to the camera or another actor/actress in the film. I enjoy watching and listening to her. She's a pretty good actress in many of those low budget short films. There may be some cases where I can bear low music in the background, but for the most part, I prefer none at all when extended dialogue is involved.