I'm just going to critique the flatwork since my focus is dresage, not jumping.
-lengthen your reins.
-relax your arms and let him reach for the bit, the connection from your hand to his mouth should feel like an unbroken stretchy band. Right now he is behind the vertical and tense, avoiding your contact.
-keep your thumbs on top and your elbows closer to your sides so you don't tense them.
-roll your shoulders back and sink more into yourself, try not to slump over. Keep your spine tall but soft.
-keep your toes parallel instead of pointing out.
-avoid gripping with your leg, particularly your lower leg.
-I won't touch on stirrup length/seat placement much since again jumping work is not my forte.
"The trouble with the world is that the stupid are certain and the intelligent are full of doubt"