Adorable pony! (Definitely an eventer)
People may disagree with me, but it looks like you're riding him like a pony jumper with your hands, and not a hunter. I'd put your hands a little lower down his crest, put them closer together. In the first video, at 5 seconds, you put your hands level and directly above your breast collar whatchamajigger, and he immediately got lighter in his back, but then when you moved your hands so did he. It may be something to try at the trot again, and at the canter.
If he gets too fast, don't be afraid to push him into the bridle with your leg and seat between fences! He's probably familiar with that, and it looks better than using too much rein. Not that you are in the videos, but just in case. =)
Last edited by kerplop; 08-06-2009 at 02:46 PM.