When Led Zeppelin sold 120,000-plus copies of their self-titled DVD in one week, it confirmed a new niche in the DVD market. Already a significant moneymaker for films -- roughly $8.6 billion in 2002 -- the DVD is fast becoming a favored medium for music, too. ''This is a new way for the fan to live in the artist's world,'' says DreamWorks marketing exec Darin Soler. Music DVDs, which have often consisted of concert and video footage bundled with a few bonus audio tracks, have never sold as well as traditional CDs. But increasingly they have become a lucrative way to capitalize on a star's success. For instance, coming off his quadruple-platinum ''Get Rich or Die Tryin','' rapper 50 Cent was able to pad his pockets with his New Breed CD/DVD, which sold 246,000 copies its first week. What the Zeppelin DVD shows is that rabid fans will shell out for concert and video footage alone. ''I don't think [the music DVD] will ever be as large as the theatrical DVD,'' says Billboard's Geoff Mayfield, ''but it will be meaningful in and of itself.''