that's a long video, with a lot of trotting, and I thought i wasn't going to see any change, but after the midway point, she got a bit looser and you started to find her mouth and I saw some moments of connection where she seemed willing to relax a bit in her neck and lower her nose a bit, and she didn't lose her impulsion , what she has of it.
I know she's a qh and it's her natural stride to trot like that, and you don't want to push her out of that, but you want her to settle into it a bit more, too, before you do anything with her head. kind of envision her wanting to go somewhere, like home, and having a long way to trot, so though she is moving out with energy, she's not rushing. that kind of feeling where the hrose really wants to get somewhere but not exhaust themselves, and has no feeling of panic. that's how you want her trot to feel.
you might try completely putting both hands forward, or, put the reins in one hand, the other on your thigh, look out somewhere in the distance, and see if you can't get her energy to cue into yours which is all about movingforward with loose energy .
Also, posting with the reins in only one hand will verify if you are using them in any way to balance off of.
at the canter, sit back a bit more.
I have the same problem , so though I might say this as a bit of advice, it's what I need to do, too. I'd sit back on her, hold the reins in one hand for a bit and aske her to canter on. then try taking up more contact.
also, in a general sense, do more changes; speed up/down within the gait, stop/start, change gait, change directions, stop and drop the reins, hug, then go on.
she is growing up and has been offering you a much more cosistent trot rythm, which is good, and your lower leg is getting really steady and quiet.