As a 16-year-old who lives with his family of five in Framingham, Mass., Riley Idelson’s life ought to be pretty carefree. If only he knew how many people are desperate to find him and put him under surveillance.

More than a year and a half ago, the teen had a TV with a cable box removed from his room. When he wants video entertainment, he turns instead to his computer, where he taps into Google’s YouTube or Twitch, the Amazon-owned live-streaming outlet for videogame play. “It’s more of a community and I like to be part of that instead of just watching regular TV,” Idelson said. He still has favorite TV series, binge-watching “The Walking Dead” or “Daredevil” by using Netflix, but samples them when the mood strikes, not at a certain prescribed time and date. “I don’t like to have a time frame,” he said. Sometimes, Idelson and his friends will get together to watch something, but they usually do it by connecting to each other through Skype and going to the same selection on Netflix. “We put the loading thing on zero, count down from three and click at the same time,” he explained.

Idelson is just one member of what has, for the media industry, become a growing legion of missing kids. Toddlers, pre-teens and teenagers all like to watch TV. They simply don’t do it in ways that can be measured and chronicles to get more money from advertisers. Big media companies like Time Warner, Viacom and Walt Disney are pressing to change that — quickly.

An industry-backed research group recently launched an experiment in trying to capture the video consumption of a new generation that considers the TV to be just one screen among many. The Coalition for Innovative Media Measurement, a group backed by Time Warner, Viacom, Procter & Gamble, Disney, NBCUniversal and others, has recruited a panel of 500 households with at least one member who is between 2 and 17. Using TiVo and a meter on a router bringing broadband service into the home, CIMM will try to measure any and all video activity: second-by-second viewing on TV; video-on-demand; DVR playback; and “over the top” video streaming. Measurement apps will be placed on personal computers, game consoles, smartphones and tablets. If successful, the effort might help the companies devise a new model that looks at total video consumption, rather than the dwindling number of kids watching “old-school” TV at a certain date and time.

“If you’re selling advertising on television and your kids are now moving off the linear television that’s measured by Nielsen and into time shifting, video on demand, ‘over the top,’ the streaming of mobile devices — all of that is not being added on and you’re losing revenue,” said Jane Clarke, chief executive of the organization. “If we think it’s bad for adults, it’s getting worse for kids.”

Indeed, Nielsen data suggests some of the biggest purveyors of kids’ entertainment have experienced significant drops in “traditional” viewership in just the last five years. The Disney Channel won an average of 925,000 viewers between 2 and 11 over a seven-day period in 2010, according to Nielsen. In 2015, as of July 26, the average viewership was 640,000. Time Warner’s Cartoon Network has also experienced dips: The average in 2010 was 573,000; in 2015, it is 497,000. And Viacom’s Nickelodeon has seen the same viewership tumble from an average of more than 1.24 million in 2010 to an average of 624,000 in 2015.

The culprit isn’t necessarily the quality of the programming, said Richard Greenfield, a media-industry analyst with BTIG Research. The shortfalls are the natural result of moves by a generation that has little interest in the couch-potato routine established by its parents. “There is among the younger demographic literally no understanding of what linear television is,” he said. “They live in an on-demand world, a world without ads. Netflix is the new Saturday-morning television.”

There’s a chance the companies may be too late. When Connor Cornwell is in the mood for comedy, he doesn’t seek out the latest broadcast of “Modern Family” on ABC or even an episode of “Rick and Morty” on Adult Swim. Instead, he loads up a stack of Vines from Thomas Sanders, one of the short-form video outlet’s breakout users, and sends them to the family TV set by using Google’s Chromecast. “Some are stupid but funny, and some are just straight-up hilarious!” said the 15-year-old resident of Deposit, N.Y. “I will plug in my Chromecast, grab some snacks, then look up his videos and click play. I’ll cast them on to our TV and watch for hours, sometimes,” he added.

The rising generation of video viewers — “television” may be a word from a lexicon no longer relevant to people who watch YouTube in large quantities — has already established habits unlikely to be broken. “They are seeking control and choice — ‘I want to start what I want when I want it and how I want it,’” noted Scott Hess, a senior vice president of human intelligence at Spark SMG, a media-buying agency. “If there’s a big screen in my house, I can fire up my Vine videos” as easily as watching a traditional piece of content, added Hess, who studies millennial habits. “Choice and control trump quality virtually every time.”

Combining the new-tech activity with that still happening around traditional TV is the industry’s Holy Grail. At Nickelodeon, for example, research suggests that the number of people following Nick’s 2007 hit series “iCarly” and its new 2015 show “Bella and the Bulldogs” could be comparable, except that a significant chunk of modern-day viewers see “Bella” digitally, on demand, or through delayed viewing. “It’s Nielsen plus all those other platforms,” said Russell Hicks, president of content and development at Nickelodeon. “That’s where we have to get to.”

Many of the companies want new metrics in place because they have begun creating products specifically for new kinds of experiences. A piece of content meant for TV may be ordered up along with a package of snippets for mobile phones and a coterie of games for desktop users. Many of the companies devise series that are for streaming-video users and will never get a sustained spot on the network’s linear schedule. “We want to know and our advertisers want to know at what levels and lengths of time our fans are interacting,” said Joe Hogan, an executive vice president at Time Warner’s Turner who oversees sales at Cartoon Network.

Will the industry move quickly enough to catch Riley Idelson? He has already moved from watching video to creating some of his own, like a digi-cast of his game play on Twitch. And then there are his brothers. His 14-year-old brother, Joseph, knows if he hears about an interesting show, like “The Goldbergs” on ABC, he can always find it available on demand. Grady, an 8-year-old, says he enjoys sports on YouTube, monitoring “Shaytards,” the sundry YouTube videos from Maker Studios co-founder Shay Carl Butler, or binge-watching the web series “Video Game High School.”

He still maintains one appointment with the TV set,however:  a morning view of “Curious George.” While that might offer some reason for encouragement, Grady may as well still be invisible to the media and advertising industries. PBS, the network that airs that popular series, does not run any commercials during episodes, only a small handful of sponsorship announcements before and after the programs run.