In director Sidney Lumet’s 1975 action drama Dog Day Afternoon, Al Pacino plays a first-time crook who attempts to rob a bank in Brooklyn. Informed by his previous job behind the teller, he has insider knowledge — but things go wrong, of course, and the police soon arrive, along with a media scrum and a crowd of onlookers who gather outside.

Holed up in the building with a bunch of hostages and no option of a clean getaway, the protagonist answers the telephone and discovers he’s talking to a TV journalist broadcasting their conversation live on air. The robber’s obnoxious anti-establishment opinions (“You’re gonna see our brains on the sidewalk … gonna show that on television?”) were beamed into the lounge rooms of everybody watching from home.

But that’s just in the movies, right?

Not exactly. That actual interview might not have taken place, but Dog Day Afternoon was based on the real-life story of bank robber John Wojtowicz, whose legendary 14-hour hold-up — full of interactions with the media and public outside — made him a celebrity.

Australia experienced a horrifyingly real dog day afternoon yesterday when self-proclaimed cleric Man Haron Monis held 17 hostages at gunpoint inside the Lindt cafe in Martin Place, Sydney for over 16 hours. Tragically, three people (including Monis) were killed.

Details of exactly what transpired inside the building will become apparent as the people involved tell their stories. One thing for certain is that Monis attempted to use media outlets to pass on his demands. Hostages inside the Lindt cafe contacted Sydney radio and television stations including Channel Nine, Channel Ten, 2GB, 2UE and the ABC.

“They talked about a password they would give me in 10 minutes. I have no idea what that means, what it’s about,” 2GB presenter Ray Hadley said. “I could hear the person in the background giving instructions to the young man I was talking to.”

According to Hadley, Monis wanted the hostage to speak live on air, but that request was denied. You’d be hard pressed to find anybody who would argue Australian media outlets did not show diligence and restraint by refusing to provide the gunman a platform. They did the opposite of what media outlets do in the movies: cross live to the scene, speak to the perpetrator on air and watch the ratings soar.

The cold truth, however, is that Monis didn’t need traditional media companies to get his message out there. Just as bloggers and social media users have taken advantage of new and emerging platforms to circumvent the old system, creating personal brands and moments of cut-through “viral” content, so will the criminals of the future.

Man Haron Monis was 50. He did not grow up in a time when (unlike now) sharing status updates and posting visual content to social media platforms was considered as perfunctory a part of day-to-day existence as taking a shower or getting dressed. When that change, partly generational, occurs, terror will go viral and regulators will be rocked to the core, madly scrambling to come up with new solutions to old problems.

An assailant could live tweet his own hostage takeover. He could use his smartphone to upload videos, photographs and messages onto Facebook, YouTube, Twitter, Instagram or perhaps a website hosted in a country with relaxed internet regulations, such as Sweden. He could have multiple accounts so that if one goes down, another goes up.

Yesterday, Facebook swiftly removed a “Lindt cafe bombers supporters Facebook page” and reportedly urged anyone who saw similarly offensive accounts to report them. But such reactive measures are only the tip of the iceberg. When it comes to not giving criminals a platform and not jeopardising police procedure, challenges in the future will be less about how traditional media companies collaborate with authorities and more about social media networks working proactively to shut down contentious or downright dangerous accounts.

From an audience perspective, social media users will be voyeurs — as viewers have always been. Terror can now unfold in real time: on your phone, on your computer, on your tablet device and soon to be on your wrist via your smart watch.

Following streams of information in ways still very new to the human experience — through a constant flow of updates on your Twitter feed, for example, crammed full of speculation, opinion and the occasional fact — and can lead cyber onlookers to become so hooked on absorbing threads of rolling updates that the desire for constant information can obscure appreciation of real lives in real situations.

This is presumably what happened to self-professed social media “goddess” Laurel Papworth, a teacher at Sydney University, who reacted to news of the siege yesterday by asking (complete with sad faces) where Lindt cafe’s social media manager was, as if being on Twitter somehow entitles us to front-row seats to a crisis.