Old shows repackaged onto DVD click with TV viewers.(Chicago Tribune)

Newly released on DVD, "Buffy the Vampire Slayer" is out to kill the competition in sales. And so far, she's doing the same sort of job on them that she has done for years with demons, monsters and the undead.

Even before its debut, advance orders for the first season of the popular TV drama about a heroine battling both bloodsuckers and typical teen-age problems already had pushed it to the top of Amazon.com's DVD sales list, beating out such movie titles as "American Pie 2" and "Moulin Rouge."

"Buffy" is just the latest example of a rapidly expanding media trend: studios repackaging television programs (from series seasons to miniseries to made-for-TV movies) to capitalize on often-rabid fan bases. This increasingly lucrative market combines the digital clarity and compactness of a maturing technology (DVDs) with the growing reach of television (especially cable) into niches often thought reserved for the video release of movies.

And these TV DVDs often offer the same features as movie DVDs: outtakes, narratives by stars or directors, documentaries, all at a relatively modest add-on cost to the producers.

"It's just a way to extend the moneymaking opportunity for the TV series," said Andrew Johnson, vice president of consumer …