Erm, hard to say without video of the actual behavior, but if he's only ducking out in one direction that tends to be more of an off-balance, stiffness, or confusion thing. If he was barn sour I would expect him to be "pulled" toward the barn no matter which direction you're taking the jump from. Maybe, on the ground, drive him over the jump without going over yourself? Stand beside the jump and encourage him to go forward with a lunge whip? Just be sure to be quick on your feet if he decides to duck out in your direction. Like I said, it's hard to give good advice without seeing the actual problem, but I don't think that barn-sourness is the issue, given the video you posted.
A stubborn horse walks behind you, an impatient one in front of you, but a noble companion walks beside you ~ Unknown