So you are riding FEI Juniors - that's awesome! Good for you for taking the leap.
A couple things to consider in general about riding the FEI Junior tests.
First of all in most places (North America and in any FEI sanctioned competitions) you will be required to wear a short dressage jacket and an approved helmet in competitions. I don't know how the rules are where you are competing though.
Next thing to consider is that this is an FEI level and you are being judged to an international standard. The scoring for an FEI Junior test is going to be harsher than in the corresponding national level (For North Americans - this is 3rd/4th test one). The judges are expecting to see a Junior on a well schooled horse that has already been trained to, and beyond, the level.
Now for the critique:
The Trot - overall there is a lack of collection, the horse needs to rock back onto the haunches and develop more cadence. Right now the trot is choppy and very "up-and-down" and does not give you a place to sit. This is especially evident in the extended trot where the horse is tugging itself along with the front end and you are forced to lean forward and bounce along. Half halts, transitions and lots of long and low work will help this.
(To MBP - about the extensions - perhaps in the lower levels that is acceptable, but on an FEI horse you need to really feel the horse powering off from the haunches in the first stride. When the horse is doing a correct extension it feels like a freight train and you have to half halt and contain that.)
Now for you in the trot, you sit nice but it appears that you are not balancing and preparing the horse for any movement. In the corner before the shoulder in you have to half halt and prepare to bring the shoulders around in a controlled manner, in the shoulder in you have to half halt and bring the horse into the volte on a line and then you have to prepare the horse to straighten and ride into the next volte. You have to ride 5 meters ahead of where you are currently and not just kind of fling the horse into the next movement - preparation is how "8"s are made. Then your half passes. These are actually your worst movement in the trot as they are ridden incorrectly. The first half pass (to the left) is videoed from a great teaching angle. Where the videographer is standing, in that half pass it should appear as if the horse from the shoulders forward is trotting straight towards the camera, as if on a diagonal. The inside leg keeps the shoulders going straight ahead while the outside leg bends the haunches around. The second half pass shows how poorly the movement is executed and is more in line with what the judge is seeing. The horse is resisting and the haunches are days ahead of the forehand. The forehand MUST ALWAYS lead. Always, always, always. Riding with the haunches too far ahead and the forehand positioned incorrectly causes the horse to have to resist and fling her neck around to stay balanced. In a correct half pass, the front legs are tracking straight on a diagonal line and the haunches are bent around, but the forehand is still leading.
The walk - Again the horse is lacking collection. She is also going completely lateral and shows no difference between the collected, extended and medium walks as well as being resistive. What I would work on here is taking her to a halt and wait for her to be still. Then ask for one step and then halt again, take a step, halt, take a step, halt. And do this until she will wait for you. Try to get the halt on a seat aid that she will listen to while walking. I'm not going to critique the walk pirouettes as the horse is obviously blowing right through the aids in both of them.
The Canter - the mare has a great naturally uphill canter, but you let her get away from you. Yes she is tense - don't be afraid to put an aid on her though. You definitely ride like a passenger through the whole canter tour and again are not preparing her for any movement, not sticking to your lines and not half halting. Every three strides in the collected canter I want you to half halt so hard you could do a rein back. AND THEN three times in each corner AND THEN before and after every movement you need to half halt again. And for goodness sake get those haunches over to the right. Put your left leg on hard until she yields and raise your left hand up about a foot if that doesn't work. Those hind legs must be in a straight line right behind her front legs. The more direction you give the horse and the more you tell her, put your body here and go at this speed and do not go faster, the more she will relax.
As far as the changes you need to half halt so hard you feel like you could do a rein back, ask and then half hat so hard you feel like you could do a rein back. I can see the changes are in there - you just have to ride them.
Overall - I see a talented horse and rider with potential for some great scores. However. You have to get in there and ride. Yes the horse is tense and forward. Put more aids on then. She is obviously the alpha mare in this relationship and takes over in the test because you aren't there to take that role. Ride like the herd boss. Ride exactly on your lines at exactly the speed you want with the horse precisely lined up as you want her and do not expect any less.
You sit very well and have great hands and posture. She's not going to buck you off, so you need to learn to use your equitation to be more of a driver and less of a passenger.