The growth of Web video and viewers’ eagerness to preview programs on the Internet is changing what fans buzz about in the television industry.

Until recently, Hollywood insiders who actually saw the pilots and new shows formed the opinions that created fan buzz. Now more fans will be able to see previews and pilots online through outlets such as NBC’s First Look Web site, turning them into tastemakers.

The buzz factor of a TV show or a star can help ad buyers gauge whether a program will succeed. Interpublic’s PropheSEE product listens in on Internet chat rooms, blogs, Web forums and message boards to analyze what people are saying about what’s on TV and upcoming shows, said Stacey Lynn Koerner, president of Interpublic’s consumer experience practice.

This year, Jeri Ryan, who will star in CBS’s Thursday-night drama “Shark,” is among the actors and actresses in successful pilots generating the most buzz. Two of the actors generating even more buzz were in shows that did not make their network’s fall schedules: Nick Lachey, who was in “She Said/He Said,” a pilot for The CW, and Denise Richards, who was in ABC’s “Secrets of a Small Town.”

TV fans are filling Web chat rooms with more postings about schedule changes for their favorite shows than actors and actresses, Ms. Koerner said.

NBC’s “Scrubs,” which won’t appear until midseason, is generating the most buzz with fans, she said.