First of all, your horse is beautiful! There was really only two things I saw, and they are pretty big hard things to achieve with horses.
Agreed with posters above. When you were sitting, your body was a bit tense, meaning your arms were tense, which led to your hands "gripping" the reins and pulling on your horses mouth a little bit, and I also saw that as a result of this, your horse was quite tense in his neck. He/she was holding it up high and arched and tense, but wasn't quite truly on the bit.. So, I would try RELAXING! Just let your body AND reins go loose, and really use only your seat and legs to stay on, dont tense up your upper body, and just do this for 5 minutes when you ride each day, and gradually start doing it more, and if you feel yourself clamping up, take it down a notch. You do a good job following with your seat, you just need to figure out how to follow with your upper body.
Another reason why your horse's neck was arched and their head was behind the vertical, but not on the bit was that your reins were a bit tight, and I feel like your horse will be a lot more swingy and collected with his/her movements if you loosened up yourself and your reins! Teach your horse to round himself with very minimal rein contact, basically right now you and your horse are relying on your reins for your horse to round, whereas you want to use a lot of your body also. The biggest thing I saw with the reins was at the canter. The walk and the canter have a lot of movement with the head, and your horse needs a little looser reins and following hands. The horse was struggling to canter with your tight grip on the reins there, so loosen up and follow some more. I also saw your hands were going up and down, so try to keep them in one place..
Oh and, LOOK UP!!
Overall great test, just a few little things to work on.