I think the source of her unhappiness is your riding (don't take offense...any horse's problems are always the rider
). You don't really move with her, when you were trying to post you were off rhythm and as a result, sitting too hard on her back. Your hands also bounce around and you don't have a steady connection with her mouth.
Jumping wise...you don't stay with her. You seem to anticipate the jump and lean forward too soon. Then you end by sitting back too soon and bounce around while trying to get your balance back. Your hands don't move with her mouth and you end up jerking her mouth. Practice a crest release before attempting automatic. I'm not a big fan of doing the crest release because I think it's more of a crutch, but in this case, with a green horse, you don't want to sour her from jumping because her mouth hurts everytime she does it.
You and share a common flaw- bent wrists. At 1:45 you can see your hands invert while trying to stop her. That means your reins are too long and/or your hands are too close together. You can also see your reins are way too long at 2:03, they're flapping around like crazy. Make sure to keep your wrists straight at all times. Easier said than done, I fight with mine all the time.
After the jump at 2:45, you brought her down to the trot, then asked for the canter and she was on the incorrect lead. Never let her do that or it will be a habit that is hard to break.
At 3:34 you jerked her hard in the mouth again. I noticed when you are trying to slow her down or stop, you look down which causes your whole body to collapse and then bounce around. Not a pretty or correct transition. Sit up tall, look forward, and relax your arms to allow for her head to naturally lower when she walks.
She's a cute horse and I think she'll do well with correct training. If I were you, I would forget jumping for now and take some serious dressage lessons. It will really help you get a feel for how to connect with your horse's mouth without being harsh or inconsistent, as well as how to properly use your body to cue her.