Posture looks ok, and contact also seems fine.
However, the horse need to go more forwards, that is called sleeping trot. Up it a notch and it will be much better ( harder to sit though too :P)
Your sitting trot is quite nice, but you need to work on your legs, trying to keep the toes a bit more paralel to the horse, heels more down, and putting leg on the horse doesnt mean using the heel ( which I assume you know) but in the video it looked like that every now and then you use your heels to get him to do something.
Rising trot looked ok, apart from the same leg thing, it moves too much. Leg doesnt have to move unless necessary - which it shouldnt be all the time, as the horse is supposed to keep a rythm itself after the first command, not need a nudge of going forwards every 2 steps..
So basically, you need to work on controling your legs, heels down will help, train the horse to keep a stronger rythm with more energy and going more forwards, and then you can also start trying to put your hands a bit higher up and closer together, more like higher class dressage riders do :P
Hope anything here helps :)