Hey there :)
I watched the video and from what I saw, you are right about your canter, you need to be more still, but not stiff. just stay with the horse. You also need to place your inner leg more on the horse to tell him, that he should go into working canter - only your leg asks him to move forwards, your body just moves with the movement of the horse. I know it doesnt come easy, but its easier to jump if you can sit a canter as well as possible, because in the jump you have to feel the horse and move with him as well ( i had many bad jumps just because due to stress etc I didnt feel the horse.. )
His canter is a little bit too lazy for jumping, it should be more forwards. Trot - you do a good hunter's seat, however in raising trot you could ease up a bit, not that much effort is needed - again, let the horse throw you up and sit back down.. its hard to explain but putting too much effort into trot means we become robots that just try to raise up and down on the count of two, not following the horse... the more you feel him, the easier it will be. doing changes between raising trot, sitting trot and hunters seat can help :)
The jumps looked alright. ofc there is space for improvement, but thats for everybody - grand prix jumpers dont sit perfect either :P
Dont take this critique negatively, I take into account that you havent ridden for a while, but these are just a few small things to try to keep in mind when riding. And once you get all the things "feel the horse, sit straight, heels down, inside leg, outside reign etc" in your mind at the same time, you will sit very good and succeed. and later on those things will happen automatically :):)
Keep working, dont stop!