Smile, You’re on Candid Webcam; A YouTube stunt shows how easy it is to collect personal information from social-media posts

Smile, You’re on Candid Webcam

A YouTube stunt shows how easy it is to collect personal information from social-media posts.

L. GORDON CROVITZ

Dec. 1, 2013 6:34 p.m. ET

More than one billion people now use social media around the world, but users are still figuring out how much privacy they are willing to trade for being able to share with their friends—and sometimes with strangers. Comic Jack Vale, who has a channel on YouTube featuring hidden-camera spoofs, recently conducted what he called a “social media experiment prank.” He went to a shopping district in Irvine, Calif., and searched social media services to see who was nearby and what he could learn about them.“I wanted to see how easy it would be to get personal information from complete strangers,” he explains in the video’s introduction, “and while I’m at it, of course, freak ’em out a little bit. Keep in mind when you watch this video, I got all of this information just by searching their personal social media posts.”

He gleaned most of his information fromFacebook

, FB +1.12% TwitterTWTR +1.64% and the photo-sharing site Instagram, plus geolocation via smartphones. He was able to call out to people on the street by name. He shocked a family by referring to their pet lizard, congratulated passersby on their recent birthdays, and told others of the meals they had just eaten. Among the reactions: “Wow, you’re tripping me out right now,” “That is really creepy,” and “Ew!” One man was unamused: “Thanks for invading our privacy. I’ll call the police if you do that again.” (Watch the video at http://bit.ly/vale1202.)

Mr. Vale explains in a follow-up video how easy it was to find the personal information. The lesson: “Your information isn’t as private as you might think it is to total strangers.” The prank video has been viewed more than 2.5 million times.

Debates about privacy tend to be conducted in the abstract by regulators, lobbyists and theorists—not by actual users of social media. The Federal Trade Commission has negotiated 20-year consent decrees that give it broad authority over the privacy policies of companies including Facebook (which now owns Instagram) and Google. GOOG -0.33%But regulators and social-media companies can only guess where users want to set their privacy trade-offs—something the users themselves are still deciding.

The good news is that any need for regulation is falling as people better understand the trade-offs they’re making, and as new companies offer greater privacy to those who value it.

A schoolteacher recently wanted to remind her students to be careful what they post online. She posted a photo of herself on Facebook holding a sign that read, “I’m talking to my Fifth Grade students about Internet safety and how quickly a photo can be seen by lots of people. If you are reading this, please click ‘Like.’ Thanks!” She got more feedback than she expected. People edited her photo to replace her face with those of actors and a smiley face. Others Photoshopped the sign into an Alcatraz prisoner ID and the Declaration of Independence.

Microsoft MSFT +1.41% is trying to use privacy as a way to compete with Google. It recently launched its Scroogled Store online, “dedicated to exposing Google’s violations of your privacy.” You can order coffee mugs, T-shirts and other gear with slogans making fun of its competitor. Microsoft has argued that Google goes too far by targeting ads based on the content of emails and sharing contact information with others. Among the Microsoft slogans are “Keep calm while we steal your data” and “I’m watching you.” Skeptics will point out that Microsoft also uses personal information to deliver ads on Bing and only wishes it had the information Google gets from its Gmail, YouTube and Android.

The truism rings ever more true that if you’re not paying for the product, then you are the product being sold. Facebook recently updated its privacy settings to make clear how focused it is on serving its paying customers: advertisers. Its “sponsored stories” program rebroadcasts favorable comments users post about products to their friends. Google recently launched its similar “shared endorsements” program that will place users’ names, photos and favorable comments on ads running on any of the two million websites belonging to its ad network. New services such as Snapchat offer “ephemeral” communications, which disappear after the recipient views the video or other message, allowing more-private communications.

Many people regard being “sold” to advertisers as a fair trade for the otherwise free services they get from Facebook and Google. But Mr. Vale’s video is a useful reminder of how much privacy they’re giving up.