I don't see anything unusual in the video, other than the facts of war.
The convoy is lightly escorted. they had truck number 1 fall over and number 5 simply stopped. They still had trucks 2, 3 and 5. Only one humwee escort could have stopped to try and help, which most likely wasn't even the one in radio contact with the truck driver. On such a narrow road it would have took some time to turn around a humwee, let alone if you'd try to pick more humwees from further ahead. The other humwees have heavy trucks trailing them at fast speed, they had to keep going and escort them out of the hell hole.
It was an ambush, they had no idea of the extent of it; it could been a light or strong ambush. Turning around and then stopping there with a single humwee could be nothing short of a suicide. Instead of a possibly lost driver, there'd be the unit of a humwee lost too. One less escort for the ambushers to worry about. There wasn't strong enough escort to begin with.
The worst thing you can do in an ambush on a narrow road is to stop and try to turn around. You can't stop to think, you must either run through and hope for the best or then you'll have to stop half the convoy and slow down the rest. By stoppping there you won't achieve anything else than becoming a sitting duck. You can't effectively fight back against an unknown enemy which is all around you, while the enemy has a perfect view on you and your numbers.
They did what was the best choice for the situation. They reorganized when they were able to and turned back to retrieve the driver.