By Adam Brookes
BBC News, Washington
The camera shows a group of Afghan soldiers standing on a cold dusty plain, listening to an American instructor. He is showing them how to use a new American rifle.
In many Afghan units, the old AK47s are being thrown away now. The new Afghan army will have new weapons: refurbished M16s.
The new weapons may be more powerful. In a firefight, they may give Afghan troops an edge over insurgents who use Soviet-era AKs.
But the new rifles are also unfamiliar. They require more maintenance, more care.
The camera shows the Afghan soldiers hunched against the wind, as the instructor talks them through the basics of the M16 rifle, through a Dari interpreter.
The film I am watching was shot by an American lieutenant: Alan Campbell, a US Army reservist in his late twenties. He trained Afghan troops for nine months.
His video is instructive. It exudes a sense of the colossal task facing American trainers as they try to assemble a modern fighting force in Afghanistan, one that can tackle the Taliban, defend the central government, and - one day - allow US, British and other Nato troops to go home.
When I interview Alan Campbell, it sounds to me as if he found the young Afghan army troubled and unsure. He says corruption was a "serious problem".
"Corruption was big: money, pay, accountability for soldiers, accountability for weapons, accountability for sensitive items, vehicles, fuel, ammunition," he continues.
"In the big picture, that's a big problem."
US officers have told us privately of equipment issued to Afghan units disappearing and US troops finding it on sale in the local markets.
They also told us about Afghan army vehicles that appear to get two miles to the gallon of fuel.
"Either there's a leak in the tank, or that gas is disappearing," said one officer.
A Pentagon report issued at the end of September spoke of "major challenges" facing the development of the Afghan National Security Forces (ANSF).
It pointed to insufficient leadership capability, shortages of essential equipment, and the time needed to develop "ethical leaders".
Ethnicity, too, causes problems in the new Afghan army.
Officers of different ethnic backgrounds sometimes would not talk to each other. Others held their rank because of who they knew, or where they were from.
"Nepotism in the army is probably one of the things that hurt them the most," said Alan Campbell. "In the long run that has to be overcome if they are going to take over control of their country."
It is not only junior American officers who worry that the effort to build the Afghan armed forces is facing serious problems. I went to a conference in Washington recently on counterinsurgency. It was attended by the US military's foremost thinkers on the subject, and I found these concerns echoed right at the heart of the counterinsurgency elite.
Col Jeff Haynes, a Marine who oversaw US teams training Afghan troops, says that building the Afghan armed forces is "utterly central to all US and Nato strategy".
US trainers say the Afghan army still has to make much progress
"Standing up armed forces in Afghanistan is huge. I cannot overstate it. They are the ones who set the conditions on the battle space, that set the conditions for governance."
He acknowledges that he encountered corruption and the nepotism. But he warns against underestimating the potential of the Afghan soldier.
"This corruption and cronyism stifles initiative," he says. "But I don't want to paint a completely bleak picture - there are pockets of brilliance and we need to expand that."
But US officers say there are not yet enough pockets of brilliance. Only about a third of Afghan army units can operate independently, we are told.
'Lack of leadership'
"And the less capable units," says Col Haynes, "are in real trouble".
He reels off a bleak list of what he found in the poorer Afghan army units: "Disregard for the mission, criminal activity, poor equipment, a lack of fuel, a lack of water, uniforms that were not worn remotely the way they were intended to be."
For Col Haynes - who is now retired from the US Marine Corps - the central problem was with leadership.
Much of the Afghan officer corps, he says, has not yet reached the point at which it can realise the potential of the tough, willing Afghan soldier.
"When you have poor leadership it starts at the top and it goes all the way down to the individual soldier."
President Barack Obama is now pondering what to do next in Afghanistan, whether to send thousands more American troops there.
Whatever he decides, one element of the strategy will remain constant: only when the Afghan security forces are ready and able and willing to take up the fight, will US British and Nato troops be able to pull out. And at the heart of the American military, they simply don't know when that will be.