New York, United States - Videos of Iranian student Neda Soltan collapsed on the ground after being shot during protests against vote-rigging in June 2009 still have the power to shock.

With a bullet-hole in her chest, the 26-year-old fixed her eyes on the lens of an amateur film-maker in a gut-wrenching stare during her final moments.

Seconds later, blood trickled, then gushed, from her mouth. Hours later, graphic footage was uploaded to the video-sharing website YouTube and Soltan rapidly became a cause célèbre of the Green Movement and Iran's worst unrest since the 1979 Islamic Revolution. TIME Magazine called it the "most widely witnessed death in human history".

Protesters carry pictures of Neda Agha Soltan outside the United Nations headquarters [AP]

Anti-regime protests ultimately failed to yield reforms and, five years later, another YouTube clip sent shockwaves around Iran. This time it was for fun - not politics - with six fashionably dressed Persians dancing and lip syncing to Pharrell Williams' song Happy, imitating the official video of the catchy global hit.

The three men and three women - who broke Islamic codes by not donning headscarves in the video - were arrested for "obscene" behaviour. They were later released after expressing remorse.

These viral sensations in authoritarian Iran showcase two sides of video-sharing via YouTube, which began 10 years ago this week. 

Times are a changin'

Soltan's on-screen death revealed how the growing availability of smartphones and camcorders was helping citizens document abuses and undermine Iran's strict rulers. The Happy video showed that, a half-decade later, widely disseminated videos were not enough to budge the country's hard-liners.

They also cast light on a darker side of video-sharing, former US ambassador Mark Wallace told Al Jazeera.

"Soltan is certainly iconic now, but what frightened me is not the fact that the image escaped but the fact that the regime was also using these technologies," said Wallace, who now runs the Counter Extremism Project and an online campaign against Iran.

"Many videos got out there, but many videos didn't. Many smartphone users were tracked, tortured and imprisoned by a repressive regime that severely limits internet use and misuses technology for the purposes of oppression."

On April 23, 2005, Jawed Karim, one of YouTube's cocreators, uploaded a 19-second clip of himself at the elephant enclosure of San Diego Zoo - the first video shared via a site that nowadays has more than one billion users, receives uploads of 300 hours of content each minute, and has viewership rates growing by 50 percent every year.

In the maiden clip, Karim observed that elephants have "really long trunks, and that's cool" - setting a dumbed-down tone for a site that has become famous for videos of cute cats, laughing babies, sneezing pandas, and animals playing keyboards.

South Korean singer PSY [AP]

Its heaviest traffic is for pop videos, with South Korea's Psy still topping charts with 2.3 billion views for his 2012 anthem, Gangnam Style. Online gamer clips have proved unlikely hits, with Felix "PewDiePie" Kjellberg ranking as YouTube's biggest star, attracting more than 36 million subscribers to his wacky video game montages.

Despite creating a hitherto unavailable video library, scholar Michael Ahn said YouTube has not necessarily made us better-informed. Viewers have a more visceral response to video clips than to long-winded articles in the New York Times, he said, and grow accustomed to short catchy content, often within the 140-character confines of a Twitter missive.

"It's information overload," Ahn, a technology and governance researcher at the University of Massachusetts Boston, told Al Jazeera.

"People get used to communicating with condensed information, images and the minimum amount of text. It's not that people are getting dumber, but they're becoming less textual and more emotional in their responses."

Looking for laughs

Pew Research Center found that online, US adults were mostly interested in clips of comedy (58 percent) and instructional "how-to" videos (56 percent). News (45 percent) and politics (27 percent) were less popular, according to the 2013 survey, and appealed to wealthier, better-educated users.

Nevertheless, YouTube's serious side extends beyond Iran.

The video logs of activist Asmaa Mahfouz helped spark the 2011 protests against former Egyptian president Hosni Mubarak. The following year, women-only punk band Pussy Riot's YouTube-friendly protest in the Cathedral of Christ the Saviour in Moscow defied Vladimir Putin, then Russia's prime minister. 

With more than 100 million views, Kony 2012 showed the abuses of African children by Joseph Kony and his Lord's Resistance Army to a wider audience than any human rights campaigner had dared to imagine. Its viral popularity likely influenced Washington's decision to boost militarily aid to Uganda in its hunt for the mystic warlord's jungle hideout.

 Turkey's top court rejects YouTube ban

YouTube's impact extends beyond repressive states. In the US, videos of police pepper-spraying students at a peaceful Occupy Wall Street protest at the University of California, Davis, provoked outrage in 2011. The same went for footage of Eric Garner, an overweight asthmatic street peddler, who was killed in a chokehold by police in 2014.

"The game-changer was giving citizens on the ground the ability to document and upload videos without news organisations acting as gatekeeper. It's had a huge social impact that we're still coming round to," Anthony De Rosa, editor-in-chief for the smartphone app Circa, told Al Jazeera.

ISIL's killer propaganda

Easy uploading has also helped those who would have struggled to manage mass-media campaigns in previous decades. The Islamic State of Iraq and the Levant fighters of Iraq and Syria have won as many as 20,000 recruits from the West with the help of videos of killings and relic-destruction - often accompanied by the group's theme tune.

YouTube is blocked by many authoritarian governments; its staff members remove content that is overly gruesome or linked to terrorism. But pulling down videos of sermons from such hard-line clerics as Anwar al-Awlaki is "like playing Whac-A-Mole", said Wallace, as they are reposted by different users.

"One wonders whether the Red Brigades, the Red Army Faction and Europe's other terror groups from the 1960s onwards would have been more successful if they could hand out anything more than pamphlets and wrist bracelets," Wallace told Al Jazeera.

"Even the 9/11 terrorist masterminds didn't have these tools to recruit or spread their agenda."

The site is also a platform for zealots at the other end of the spectrum, such as the makers of the anti-Islam Innocence of Muslims video, which spurred often-violent protests in some 20 countries. Quran-bashing in Fitna, a 2008 short film by Dutch parliamentarian Geert Wilders, did little for harmony between Europe's Christians and Muslims.

"YouTube mirrors what we see across the internet, which is not one monolithic thing," said De Rosa. "It's a kaleidoscope of people, themes and memes from light-hearted entertainment to tough social, political issues and everything in between."

Who to believe?

Some question whether YouTube has changed the world for the better [EPA]

In Ukraine, where a fragile truce holds between government forces and pro-Russian eastern rebels, YouTube spreads video, views and propaganda for all sides. In February 2014, some 90,000 videos of Maidan protests were uploaded to YouTube and have been viewed 25 million times.

Clips also help narrate a four-year-old civil war in Syria that has become too risky for many media outlets to cover. Regularly uploaded footage of bloodied bodies and severed limbs is blamed on anti-government rebels and loyalists - often depending on who is doing the accusing. Syria clips have attracted some 200 million views.

Yet all this content has not yielded any landmark shifts. Autocrats still run Iran and Egypt. Kony is at large, Putin is resolute. Armed groups still make videos and, according to many activists, American cops remain too heavy-handed.

For De Rosa, the decade-old site poses more questions than it answers.

"YouTube won't change these complicated unresolved issues that play out over much longer periods of time," he told Al Jazeera. "It's a tool to address those problems, a way to disseminate information to a wider audience. 

"It's the people who see it, the viewers, who have to figure out how to bring about change."

Follow James Reinl on Twitter: @jamesreinl

Source: Al Jazeera