In the audience at a recent Natalie Merchant concert at an 880-seat theater in Los Angeles, Adam Miles couldn't focus. The man to his left was holding up his cell phone, shooting video. "Please," Mr. Miles asked his neighbor, "turn it off." A few songs later, the phone lit up again, and the San Diego harbor police officer got more commanding: "Hey, dude. You're going to have to put that away. You're ruining the show for me."

John Jurgensen has details about a new trends that's taken hold at concerts - holding up mobile devices at concerts and recording the event -- and why artists are split on whether it's helping or hurting the business.

Mr. Miles wasn't the only one distracted by the gadgetry. In the second half of the concert, Ms. Merchant paused to call out a man near the front who'd been brandishing his phone throughout. "I'm right here," she said with icy sarcasm. "This is live. This is where the show is." Then she told the audience to just get it over with, briefly striking poses as hundreds of devices clicked away.

At most concerts these days, when the houselights go down, the tiny glowing screens go up. As more fans mark the moments with smartphones, cameras and pocket-sized video recorders, a new kind of digital divide is emerging. Music lovers who try to document and share the essence of concerts are squaring off against those who think that just defeats the purpose. The debate is drawing participants from both sides of the stage.

"I'm right here. This is live. This is where the show is." --Natalie Merchant Redferns/Getty Images

Some bands, including the venerated rock groups Wilco and the Black Crowes, are asking their fans to go cold turkey on taking videos and photos at concerts. In movie houses, such edicts are meant to fight piracy and copyright infringement. In the music industry, where that ship has already sailed, these new policies are more about preserving the tribal atmosphere of a concert.

Plugged-in concertgoers are seizing new ways to participate in the show beyond simply clapping, hollering and maybe buying a T-shirt. For some, it's enough to fill hard drives with souvenir moments; others have found audiences of their own online, especially among passionate fans whose hometowns rarely show up on tour itineraries.

Chris Robinson, 44-year-old singer for the Black Crowes, isn't on board. "As a band we've been trying to string together these moments, the kind of moments I've had as a music fan that have blown my mind. That's not happening when you're texting or checking your f—ing fantasy league stats," he says. "I personally think you should be too high to operate a machine at our concerts."

When the Black Crowes decided to prohibit pictures and videos for its current tour, the band took some flak. "How incredibly lame," wrote one of many Facebook users who speculated that the group was trying to protect its ability to profit from professionally shot photos and videos.

And indeed, artists don't want to alienate the very fans who pay to see them, and often proselytize on their behalf. In an industry where album sales continue to decay, social media is the hoped-for lifeline. Acts are all too aware of how their careers can be buoyed or sunk by a critical mass of exclamation-pointed Facebook postings and Twitter links to raw footage.

"I don't think buying a concert ticket gives you the right to film. That doesn't work on Broadway or at the movies." --Jeff Tweedy of Wilco Retna

While there are still artists who cry piracy, many others have either thrown up their hands or pounced on the free promotion these videos provide. They range from young acts like Justin Bieber and Owl City, who were launched almost exclusively via online buzz, to the famously open-source group Radiohead. Earlier this month, fans released a free two-hour, high-definition video recording of a 2009 Radiohead concert in Prague, edited together from footage shot that night by some 60 audience members with Flip cams. The band joined the project by providing its own master recordings of the concert for the soundtrack.

Artist manager Ian Montone, whose charges include the White Stripes and Vampire Weekend, says his bands aren't crazy about playing to a wall of cameras. "Having the first 20 rows of an audience standing motionless and acting as ersatz cameramen can be obnoxious to the artist, other fans, and takes away from the concert experience," says Mr. Montone.

But his acts don't want to play bad cop. "Within the last year and a half it became such a losing battle," he says. "You're not going to kick out the entire audience."

When fan footage goes online, his reaction involves quality control more than copyright. He often asks the creators of shaky, murky-sounding clips to take them down, and sometimes compliments the owners of great-looking footage—while reserving the band's right to make use of it in the future.

Los Angeles music fan Tony Kim has uploaded more than 300 homemade concert videos to his YouTube channel, showcasing everyone from Arcade Fire to the Ting Tings. None of these unauthorized clips have ever been removed by YouTube, he says. Yet he recently noticed advertisements popping up next to some of them, including footage of indie rockers Metric. Since 2007, YouTube has provided a program that lets copyright owners monitor such fan-made music videos, allowing a record label, for instance, to drop in ads or "click to buy" links. Of course, they can also choose to remove the videos, or just look the other way.

A Field Guide to Live Music Online From stadium stops to coffeehouse gigs, the Web is home to more and more shows. Livestream and Ustream Gene Simmons of Kiss Getty Images Specializing in free live video streams, these sites have drawn bigger names in music as rights issues got easier to navigate. On Saturday night, Kiss goes live from L.A. and on Ustream. On Thursday night, a Maroon 5 gig in the Facebook headquarters will be carried by Livestream. Thursday night, a Spike Lee-directed concert by John Legend with the Roots live-streamed at YouTube.com/JohnLegendVEVO. livestream.com, ustream.com Wolfgang's Vault This classic-rock trove first launched in 2003, boasting concert audio from legendary promoter Bill Graham. Now it offers a mix of free and paid content. Download shows by Bob Dylan or Fleetwood Mac for about $10 each, or stream them for free. Newer acts are also added to the Vault through Daytrotter, a sister site attached to an Illinois recording studio that snags performers ranging from Justin Townes Earle to Ra Ra Riot. wolfgangsvault.com NYCTaper Pavement's Stephen Malkmus Getty Images In the tradition of Grateful Dead tapers, NYC Taper offers free audio downloads of recent New York City concerts (with permission from the bands), including a recent reunion gig by indie rock heroes Pavement. For a different flavor of live music, from Drive By Truckers to Ryan Adams, try Archive.org.

nyctaper.com Live Fix Unlike other all-purpose music blogs, Chris Catania's Live Fix blog focuses on"concert culture." It highlights bright spots in live music, like the frenzied Girl Talk concert that was professionally shot and released free online last week. Some essay-like entries explore phenomena such as a viral video from a rock festival, where a shirtless man's solo boogie seemed to spark a spontaneous dance party. christophercatania.com Flickr Browse the work of photographers passionate about capturing the light, color and movement of live music. One user group boasts about 25,000 members, many of them working shooters. The flow of crisp images, many fresh from last night's show, encompass everyone from U2 to underground Israeli rockers Monotonix. flickr.com/groups/concertshots Radiohead Radiohead's Thom Yorke Getty Images The experiments in free culture by Radiohead (above) continue. At a concert in Prague last year, about 60 fans shot the show using inexpensive Flip cameras. The many angles were edited into a single two-hour video, matched with a high-quality audio recording supplied by Radiohead itself. Stream it on YouTube or download free from the project site on one condition: "Strictly not for sale—by the fans for the fans". radiohead-prague.nataly.fr —John Jurgensen

Jeff Tweedy appreciates his tech-savvy fans. After all, they've made his band Wilco a going concern for more than 15 years. Like the Black Crowes, Wilco allows fans to make audio recordings at concerts and trade them online, for free. But video cameras, especially right up front, bother him. He says there's something more at stake than just distracting the lead singer (which is "just rude"). "I think you're surrendering your own memory to a very imperfect medium," he says. "Our memories are imperfect to begin with but that's what's beautiful about it."

Last winter, Mr. Tweedy took his family to see the illusionist Criss Angel. At the Las Vegas performance, recording devices of every kind were prohibited, enforced with a pat-down of audience members filing in. Inspired, Mr. Tweedy encouraged his band to institute its own no-cameras policy (minus the frisking).

"My sense of indignation was really roused quite a few nights," he says. "Once there was an established set of rules, I could stop talking about it during the shows."

The band posts signs inside venues and delivers an announcement over the public address system before show time. A robotic pre-recorded voice informs the audience that Wilco welcomes audio recording, singing along, shouting requests between songs and "general merriment." But "to avoid ending your evening with Wilco prematurely," it says, keep your cameraphone stowed. The venue's security guards take over from there, usually targeting transgressors with a flashlight beam to the face.

Mr. Tweedy says so far most crowds are policing themselves, and that it's paying off: "I honestly feel the crowd's engagement with the show. There's a more audible kind of reaction to different musical moments, a kind of intangible energy."

Photo and video restrictions persist in the language of many artists' tour contracts, but the ubiquity of camera phones have rendered them moot. Concert venues must be ready for everything. "It's like playing Whac-A-Mole," says Ed Stack, who manages the 9:30 Club in Washington. "Holdout artists who are hell-bent on controlling their image are becoming a thing of the past," he says. His security team will go into enforcement mode if the band requests it, with guards often sidling up to the offending ticket holder. "You get real close up to their ear and say, 'I don't want to have to confiscate that.'"

Generation gaps are a given in music culture, but age seems to have little bearing on the urge to gather gigabytes of concert footage. At a recent sold-out concert by the popular avant-garde rock act Dirty Projectors, very few of the 3,000 young fans were holding LCD screens aloft. Courtney Weisman, 22 years old, said she gets annoyed when she catches herself staring at her neighbor's mise en scene. Her own iPhone mostly stays in her pocket.

By contrast, Todd Morason, a 41-year-old eye surgeon from Syracuse, N.Y., says his high-definition Canon video camera has transformed his relationship with live music. He used to attend only a few concerts annually. He's been to more than 20 in the last year, spurred on by the popularity of his live clips of rock bands like Muse and Steely Dan, which he posts on YouTube. His greatest hit: a song by the young pop-punk band Paramore that he captured last year at the Electric Factory club in Philadelphia. Shot from the balcony, the nearly five-minute clip has pulled in more than 350,000 views.

With his online audience in mind, Dr. Morason has sought out bands he doesn't care for personally, including the prog rock group Coheed and Cambria. To keep his video quality high, he doesn't dance or sing along with the crowd, and he attends most shows alone. With his eyes trained on his camera screen, he's been walloped by crowd surfers. And sometimes the 5-foot-7 physician struggles to get a clear shot. Standing in a dense crowd at an Aerosmith concert, his fingers went numb from holding the camera at arm's length during a 10-minute jam. He recalls thinking, "I can't miss 'Dream On.' It's the anthem. I can circulate blood to my fingers later."

Some artists say the ever-present lens is forcing them to play it safer on stage, knowing that a sloppy set in front of a few hundred people can quickly ripple out to thousands of YouTube critics. Canadian indie rockers Broken Social Scene had test-driven new songs in concert for years, working out kinks on the fly. Now they only debut new material after it's been thoroughly rehearsed, largely for fear that a flubbed vocal or uneven guitar solo will draw fire online.

"We're grateful that people care enough to pay attention, but we want to be at our best," says front man Kevin Drew. He says phones and cameras are too important to the fan experience to ban them, but at a a show in Dallas last year, he leaned out and grabbed a camera from a particularly determined woman in the front row. (He says it was returned when the show was over.) Like many young people who grew up going to punk-rock shows, he was schooled in the unwritten etiquette of the mosh pit, including the importance of hoisting people up when they hit the floor. Cameras are different: "There don't seem to be any rules and people think they can do whatever they want."

Speakeasy Low Anthem Appropriates Mobile Technology

Fans can now beam a live video feed from the sixth row, using just an app, a robust cellular connection and a free account on a site such as Justin.tv, Livestream or Ustream. These companies say such activity is still nascent, but catching on as technology improves. After Justin.tv released new apps for iPhones and Androids this month, the number of users broadcasting from their phones (as opposed to desktop webcams) surged to more than 30%. In music, fans of the jam-band Phish were early adopters. Since the group reunited last year, many of its shows have been watchable online, thanks to a network of fans who capture the action live for outlets including Hoodstream and Phishtube. Phish says it's aware of the practice, but didn't want to comment on it.

Live video companies are wary that unauthorized fan streams could rankle the very music acts the sites are partnering with for official concerts feeds. For now, however, a live cellphone link from the cheap seats is hardly capable of Scorsese-style concert footage.

"If you look at cellphone streaming," says Livestream co-founder and chief executive Max Haot, "between the camera quality, battery life and network issues, it's usually not a great experience."

Write to John Jurgensen at john.jurgensen@wsj.com