—Joss Whedon to launch vanishing web series: The Buffy, the Vampire Slayer and Angel mastermind is set to release his writers’ strike-inspired web series, Dr. Horrible’s Sing-Along Blog, but will only make the 42-minute project available online for three days, at which point it will be taken down from the web. Released in three parts, on July 15, 17 and 19 respectively, Whedon says the series will “vanish into the night, like a phantom” at midnight on July 20. The ultimate goal is a DVD release, complete with extras and a musical commentary.

—HDNet and AOL Music debuting concert series: Mark Cuban’s HDNet, in conjunction with AOL (NYSE: TWX) Music, will debut a concert series on July 13. Entitled Hard Drive, the 90-minute show will open with a sneak peek segment featuring Good Charlotte before a launch in the fall. The series will showcase 13 concerts that will first premiere on Sundays on HDNet and then on Mondays on AOL Music.

—Video clip provider PopTok launches, signs major studios: PopTok, a provider of short movie and TV clips for email and instant messaging services, has launched in beta. The start-up has deals with several major studios and labels, including CBS (NYSE: CBS), Paramount, WB, Universal, Lionsgate and Sony (NYSE: SNE) BMG. By dragging and dropping video clips into instant messages and emails, users can send their favorite lines from TV shows, movies and songs to their friends. The site plans to add over 10,000 clips to its library by its public launch in fall and hopes to make money through ads, promotional deals and a cut from e-commerce transactions such as iTunes or VOD sales.

—Germany’s Bayreuth opera festival goes digital: In hopes of attracting a younger audience, the annual Bayreuth opera festival has made plans to stream live video and audio of its opening performance of “Die Mestersinger von Nuernberg” online. The catch? A fee of $77. The live premiere on July 27, however, will be shown for free at a public viewing in Bayreuth’s town square. The video will be available for paid download online through Aug. 2, with a re-edited DVD due out for a Nov. release. The hefty streaming fee is to offset the cost of filming; production company United Motion will use eight remote control cameras inside the Bayreuth Festspielhaus theater to record the five-hour opera.