Despite a lot of hype, Megyn Kelly’s interview with Alex Jones drew only 3.5 million viewers Sunday night. That’s less than a rerun of “America’s Funniest Home Videos,” which I didn’t even know was still on the air (how many videos can there be of a father being hit in the balls by a plastic bat swung by his 4-year-old son?). That episode of Kelly’s show is the lowest-rated of the three that she’s done thus far, so the execs at NBC can’t be happy.

They’re learning an important lesson they should already have known — there’s a difference between a TV star and a cable news star. Kelly was successful at Fox News Channel because the standard for success (and truth, and sexual harassment) is much lower there than it is in the big-time TV universe. It’s like when Katie Couric was hired away from NBC’s “Today” show to anchor the “CBS Evening News.” The latter hoped that all her viewers from the former would follow her, but they didn’t because the two dayparts demand different skills and exist in separate and non-parallel universes. When it turned out that she wasn’t the draw they expected her to be, Couric was yanked by CBS and replaced by Scott Pelley — who has now been similarly dragged from the anchor chair after five years of so-so ratings and will be replaced by, oh, who knows.

Meanwhile, Kelly’s former channel-mate Bill O’Reilly is making noise about how he’s going to return to the public eye — via a streaming show on his website. That’s yet another universe, one with a much smaller potential audience. Of course, O’Reilly is full of so much hubris that he’s sure the millions of fans that tuned in to his FNC show will now find him on the internet. Yeah, good luck with that, Bill. I think you’re going to be sorely disappointed. Just ask Glenn Beck, who discovered his influence had essentially disappeared when he ran off to the online-only world to not make his fortune.

Back to Megyn Kelly. Those NBC execs who signed her to a multi-year, multi-million dollar contract — but can’t love her Sunday night ratings — must be wringing their hands over the new daytime show she’ll debut this fall, taking over one of the later hours of “The Today Show.” Though no announcement has been made of exactly what that show will be (news-intensive, celebrity-guest-driven, or yet another Oprah imitation?), the network has to be a little worried that Kelly will follow the daytime disaster route already forged by other TV stars who tried to spread their wings but couldn’t overcome the gravity of the Nielsen ratings. Besides Couric (who failed in that daypart, too), the list includes Anderson Cooper, Jane Pauley, Meredith Vieira, Jeff Probst, Queen Latifah, Wayne Brady, and Megan Mullaly.

Whether this Megyn can find success at NBC is still an unknown. But she’s not off to a very good start.