I caught the last 3/4 of the program on National Geographic last night. Their attempts to purchase "assault rifles" began with them "going undercover" in licensed gun shops and asking to buy without background checks or by having the customer talk on their cell phone while negotiating with the clerks to make it obvious they were attempting a straw purchase. Just as you'd expect they were repeatedly denied and were given a few lectures on the law by gun shop owners. This was all accompanied by very ominous music and many statements by the main reporter about how nervous she was and how dangerous it was going under cover, and how anything could go wrong at any moment and she could find herself in great danger!
They also opined that they didn't get away with it only because they had tried to purchase too many guns at once, because obviously the gun shop owners would gladly risk their FFLs by breaking the law to sell only one gun.
At the last gunshop they visited, the sales clerk gave them just the sound bites they were looking for, as they asked him about the possibility of purchasing the same guns they were looking at in his store at a gun show instead. The clerk, obviously trying to make a sale, went on and on about how you have no way of knowing at a gun show who might be a criminal or whether the guns may be stolen.
Next they moved to a gun show, where they purchased several handguns (including the Most Powerful Handgun in the World!) via private sales without a background check. On their way out, they stopped by some officers who were onhand to run the serial numbers to check if any of their guns were stolen (they weren't), and the officers cheerfully provided more sound bites about the risks of purchasing at a gun show.
From there they moved on to a segment in Mexico, showing photographs of violent crime scenes and tables full of "military-style" weapons seized from drug cartels. They had a whole segment about a multi-million dollar tunnel constructed under the border where "illegal drugs flowed north, and money and weapons flowed south".
Finally, to show their theory of where these guns flowing south came from, they moved on to the segment highlighted in the video linked above, where they searched for used guns on the Internet and met up with the buyers for face-to-face sales without a background check. They did a good job of making it look scary how easy it was for someone to buy guns from a complete stranger with no background check, but I hope that any discerning viewers would look at how over-the-top they went on the first half of the show and wonder what they weren't showing at the end.
I personally do find it a somewhat concerning that a normally prohibited person could use a private sale to get around this prohibition, but this show never discussed the most important points of this issue: first, that this overwhelmingly is not how criminals acquire guns, and second, how can this be stopped without placing an undue burden on legal gun owners without criminalizing the legal transfer of firearms between citizens that actually know each other before the transfer, as is the case in the majority of private transfers?