To me... Your horse is developing to the rider. The rider in the video not only does not have a release but actually looks like they are pulling back. I don't know what ring they have the bit on (looks like yours is on the second one), but an elevator bit can be very severe, and a rather rough jolt if you don't release. If I were you I would be working this horse through bounces (with a different rider) to encourage the horse to use it's neck and jump round. I don't know how stable you are over fences, but if this were my horse (and basing of the little evidence I have here) I would rather you riding the horse. Your have a more giving hand and though you're tipping forward a bit you are certainly not jumping ahead as much or such a severity.