I agree with the above posters, that your leg is too far back O/F and toes out. Also, you're throwing your shoulder just a bit over the fence, you need to hold it still & let the horse jump up to you, this is partly what is caused your leg to slip because your body weight goes onto the neck & out of your heel. Ducking is a pretty common issue in Hunter-Jumper/Eq. Riders today, and could use some cleaning up to improve the horses jump & keep us all more balanced. Remember to wrap your calf around the horse, without pinching the knee or heel, to keep your toes in alittle more. I would also like just the slightest bit more of a bend in your elbow to bring your hands a slight slight bit higher. Overall, very nice equitation, no rider is ever perfect, a nice presence in the show ring & a beautiful horse, love his tail!