The London live stream was not an isolated incident. Last week, Raymond Boyd Gates, 29, was in court having been charged with the rape of a 17-year-old girl in Ohio. What made the case so shocking and unusual was that one of the girl's friends, Marina Lonina, 18, was in the room at the time and live-streamed the alleged attack to an audience online.

Gates and Lonina have pleaded not guilty to rape and sexual battery, among a number of other charges. The prosecutor said Lonina became excited by turning the attack – which she broadcast on Periscope – into a public spectacle, responding to the comments left by viewers.

"She got caught up in the likes," the prosecutor told the court.

Columbus police were able to obtain a copy of the Periscope video in which they say the girl appears to struggle and can be heard screaming "no, it hurts so much" and "please stop" several times.

Police say they were notified of the alleged assault not by Periscope's monitoring team, but by a friend of Lonina's, who was watching the live stream in a different state.

In recent months, a spate of criminal activity has been documented on live-streaming apps. Last October, a woman in Florida used Periscope to broadcast herself drink-driving. She was arrested after one of her viewers reported her to police. Then in November, a mother from the UK revealed in a harrowing interview that she was beaten and raped daily, and that her abuser aired the abuse live on the internet. At least one crime has been unintentionally live-streamed: Three weeks ago, a man in Chicago was shot while filming himself on Facebook Live. It is thought to have been the first time someone has been shot while live on Facebook.

And on Tuesday, footage of a brawl between dozens of teenagers outside a shopping centre in London was broadcast live on Periscope. Viewers of the eight-minute video, which showed people fighting and spitting on each other, shared the stream with friends on Twitter.

For the majority of live video users, the tool is harmless – a fun way to share intimate moments of their lives at the touch of a button. Apps like Periscope, Meerkat, Twitch, and Facebook Live host hours upon hours of footage showing a glimpse into users' personal lives. On Periscope, people are watching 40 years' worth of live video every day. Snapchat – which introduced its Live Stories feature last year – has 100 million daily active users, with 8 billion video views each day.

In a recent interview with BuzzFeed, Facebook CEO Mark Zuckerberg spoke about his excitement over the "raw" experience live video offers. Nothing can be planned with live video, Zuckerberg stressed, making it great for anybody to share "visceral" content, especially "young people and teens".

"Because it's live, there is no way it can be curated," he said. "And because of that it frees people up to be themselves. It's live; it can't possibly be perfectly planned out ahead of time."

Raw video's lack of curation is seen as a benefit, not a hindrance, to both Twitter and Facebook, two of the largest platforms offering the service. But with the colossal amount of content streamed every day, the question looms of whether social media giants can be expected to keep on top of possible crimes broadcast live on their platforms.

Both Twitter and Facebook have guidelines and a flagging system in place that aims to filter out graphic content such as pornography or overtly sexual content, violence, and illegal activity. However, the current moderation processes for flagged content at social media companies are notoriously slow and flawed. It can often take days, or weeks, for posts to be taken down, posing an obvious problem for live video considering the realms of offensive, violent, and criminal activity that could potentially be aired to an audience of thousands in real time.

Facebook told BuzzFeed News the company is working to improve its current reporting system. On its platform alone, users flag more than 1 million items of content for review every day. (Facebook hasn't stated what percentage of that is from live video.) The company says it wants to build stronger systems to respond efficiently to live streams, so it can become less reliant on users to hit the report button. Specifically, Facebook says it is planning to hire more people to review reported content.

"We believe the vast majority of people are using Live to come together and share experiences in the moment with their friends and family, so we want the Live experience to be as immediate as possible," a spokesperson told BuzzFeed News. "We encourage anyone watching a Live video to report violations of our Community Standards while they are watching; they don't have to wait until the Live broadcast is over."

"We've been working on ways to improve the Live reporting function," the spokesperson added. "We've been aggressively growing the global team that reviews these reports and blocks violating content as quickly as possible."

It's unclear whether or not more bodies to monitor live video will make a significant dent in criminal or inappropriate activity being aired live. Neither Facebook nor Twitter say they have a fast-tracked approach for removing flagged live-streamed video over content that's already been uploaded.

Daphne Keller, the director of intermediary liability at the Stanford Center for Internet and Society, recognises that the current systems in place for flagged content are slow, and says it would be "sensible" for companies to prioritise live video over older content to some degree.

"If someone thinks they are seeing a crime in the moment, like rape, it makes sense for that content to go to the front of the queue," Keller told BuzzFeed. "But the complaint system is slow, manual, and gets a lot of spam, so if you're processing that while trying to address a real emergency in real-time, you're faced with a lot of complications."

Keller says that even when a company comes across illegal content, the problem isn't removing it – that part, she says, is easy. The issue is knowing what to do next.

"If you're one of these companies, and you know this illegal thing is going on, taking it down isn't hard – getting content off the internet is almost secondary in that situation. Instead, the high priority is to do what you can to let the local law enforcement know what's going on. If you are a user and you see a live feed of crime, the first thing you want to happen is to alert the local police of where it's happening, if the location is known.

Companies can make that easier. Keller says the reporting system could have an option for 'urgent reaction' in live video.