Assuming that you are the person on the horse with the red boots, right? You are hunching over and looking down at his neck. Also make sure he is not leaning on the bit. Ideally, the poll would be the highest point on his neckline, in the video it is somewhere on his neck which isn't great. Try to keep your lower legs quiet and be more fluid with your posting. Your hands seem somewhat stiff, you want softer wrists so you can "feel" his mouth better. Really great overall for your third dressage ride, I wouldn't have guessed you were new to dressage.
Also, tell whoever is in there riding with you that they need to STOP doing that with their hands. Their horse is grossly behind the vertical and overflexing and it is very bad for the horse's neck and makes them cautious about being on the bit.