The bomb appears about two and a half minutes into the documentary. Almost comically rocket-shaped, the huge unexploded device is seen leaning against a wall supporting a steep, curved wooden ramp as a child in a stripy sweater rolls up and down it on a skateboard.
"It's actually a real bomb," says Orlando von Einsiedel, the director of Skateistan: To Live and Skate Kabul, adding that - happily - it had been disarmed. "Someone saw it lying in a field, put it on the back of a lorry and took it to the skatepark."
Unfortunately, in word association "bomb" probably ranks higher than "skatepark" when discussing Kabul. Such is the violent modern history of Afghanistan that the idea of having a functioning skatepark in the war-torn country - over a giant bomb casually propped against a wall - that undoubtedly raises eyebrows. And it was this curiosity that took von Einsiedel from the London office of his Grain Media production company to Skateistan, a 19,000 square-foot indoor skating facility in the Afghan capital, for two weeks in January this year.
"I used to be a pro-snowboarder," says von Einsiedel. "Then I started making snowboarding films and this moved on to documentaries. Now I focus on films covering social issues in conflict zones, so this seemed perfect."
Sadly for Von Einsiedel, he wasn't the first to express an interest.
Set up in 2007 by two Australians, Oliver Percovich and Sharna Nolan, Skateistan began life as a patch of land near a decrepit Soviet-era concrete fountain. Having simply taken to the streets of Kabul with their skateboards, the pair noticed the eager reactions of the local children and realised that here was the ideal way to engage with an often forgotten but unquestionably important segment of Afghan society.
Starting with three skateboards, Percovich and Nolan began providing lessons to the children, using skateboarding as a means to promote communication between youngsters across the various different ethnic and economic groups in Afghanistan. Eventually registering as an NGO and with financial pledges from several governments and hundreds of donated skateboards, Skateistan's dedicated facility opened last December on land in one of Kabul's poorest districts, given by the Afghanistan Olympic Committee.
Aside from providing free hire of skating equipment and use of the park to children from across the Afghan capital, Skateistan also offers lessons in other subjects, such as English and IT, in classrooms at the back of the facility.
The Skateistan story is clearly one that would appeal to many a writer or filmmaker. "They get about a hundred requests a week from journalists," says von Einsiedel. "Their general policy is to say no, because they don't have the resources and want to concentrate on doing the work." Von Einsiedel admits that it took a great deal of persistence on his part to persuade Skateistan to let him come over.
Skateistan: To Live and Skate Kabul, is the result of his time there, a beautifully captured and heartwarming nine-minute documentary that has been raking in the hits online, winning plaudits from across the world and is likely to take the festival circuit by storm when it does the rounds. Recently it was announced that the documentary would take part in next month's Sundance Film Festival in Utah.
The film follows two of Skateistan's students, Murza and Fazilla, through the streets of Kabul. It is Murza we see in the striped jumper effortlessly riding the "rocket wall" ramp, the park's signature (and most eye-catching) obstacle. A 17-year-old who says he's so used to seeing fighting in his country it doesn't scare him any more, Murza used to wash cars for a living, even through the winters when the bitter cold would cause his hands to freeze and crack. He is now employed by the park, cleaning the facility and helping with skate training. "Life is hard in Kabul," he says. "It is solely because of the support of Skateistan I am standing now."
While Murza's story offers a personal account of how Skateistan provided an escape route from the grinding daily chore for Afghanistan's poor, it is Fazilla whose story perhaps best answers those who might doubt whether a skating park sits high on the country's list of priorities. A 12-year-old who says her family often can't afford to eat, Fazilla works on the muddy streets of Kabul selling chewing gum to the occupants of passing cars to help her family.
According to the UN, some 49 per cent of Afghans are under 15, the highest proportion of school-aged children in the world. But like Fazilla, many from the poorer echelons of society rarely get to enjoy their youth and have to help feed their families from an early age. "They don't get a childhood," says von Einsiedel. "They're mini-adults dealing with huge problems. Skateistan is an oasis where children can go and be children for a few hours a day."
As the documentary shows her actively participating in one of the organisation's educational classes, Fazilla summarises its unique qualities. "At Skateistan I don't feel that my surroundings are ruined," she says. "I feel as though I'm in a nice place."
With Fazilla, the documentary also highlights one of Skateistan's proudest achievements; that of slowly bridging gender divisions in a land where the Taliban violently enforced discrimination against women. Sport in Afghanistan is considered an exclusively male preserve, but one of Skateistan's main focuses has been to encourage girls to get involved. Nolan explains: "There's nothing like watching an Afghan woman roll down a ramp for the first time and she's achieved something that she never thought she would."
Fazilla says that much of Afghan society is still critical of female participation in Skateistan. "When I'm skating on the streets, I can feel people questioning my right to skate," she says, adding that her own father disagrees with her hobby.
Von Einsiedel acknowledges that, while he saw no direct disapproval while he was filming, he had heard of a girl forced to leave the park by her brothers. There have also been reports of girls being beaten by their families for their involvement in the activity.
"Their opinions are meaningless to me," Fazilla proudly says. "I really like skating and I won't stop."
The documentary's final scenes show a group of children skateboarding through the bullet-riddled ruins of Kabul's once-proud King's Palace while a bemused gun-toting security guard looks on. A side effect of the civil war is the huge array of damaged and evacuated sites now available for Skateistan's children to practise on. "What's so awesome is that the kids have reclaimed these places for fun," says von Einsiedel.
"The biggest thing I took away from my time there was that the kids are full of life and energy and hope for their country. They're so acutely aware of how far Afghanistan is behind the rest of the world. They just want the war to end and to help rebuild their country."
Aside from the short, a full-length documentary, Skateistan: The Movie, is in production, though without the involvement of von Einsiedel, who says the German director Kai Sehr had contacted Skateistan just weeks before his enquiry. "It's a real shame, because I was born to make that film," he sighs.
Despite this setback, there is something else he's considering lining up for a future project: "The mountains around Kabul are immense, so perhaps something on snowboarding could work."
This version of the story corrects the name of the film, Skateistan: To Live and Skate Kabul, from an earlier incorrect version, Skateistan to Live and Skate in Kabul.