I've killed tanks solo with a rocket launcher. It takes 3 to 4 rockets to destroy one. I look for an engineer to jump out to repair the tank so I can kill him too, two birds with one rocket. You do have to have cover but it's easy otherwise. And like you said, two AT soldiers means a tank is fucked.

About the commercial, a humvee is toast against an AT soldier. And that howitzer doesn't have a coaxial gun to kill up close, and its cannon is only good for long range.