The things that I see that need some work are your hands and posture. When you are cantering, you seem to lean back. It almost looks like it is not comfortable for you when you canter because when he steps forward, your body leans back. Also, you need to try to keep your hands lower and closer together. You look very balanced and you were always on the correct diagnols. Pretty good, just those couple things.
In the beginning of the video, when you are walking with no stirrups, make sure you are bending your elbows. Start by rolling your shoulders back and squaring them, and then bring your arms back and bend your elbows a bit more. You'll find your whole posture to be straighter when you aren't hunching your shoulders. In the trot you've fixed your shoulders somewhat but I think you could still bring them back a bit more. I like that you aren't posting too high. You have a really nice quiet seat and quiet hands, too. :)
When you're cantering, it looks a bit like you are pumping with your seat. I think here you could lighten your seat a bit and tip your body forward more (not hunching forward, but more of a hunt-seat position). I also think it would help you to shorten your reins and push your hands forward out in front of you for more control. You look GREAT cantering without stirrups! It took me a while to realize you didn't have them - your leg position is perfect there.
Pause at 2:30. I love your seat there. That's where your body should be during the canter. Just push those hands forward and shorten the reins and that would be perfect.
Why does that look like a western saddle but your posting? You look good to me your hands you are right ummm it looked to me I might not be right but the first time you were cantering it looked liek you were landing on his back to hard
I post in my western saddle all the time.
If it were western, I would say lengthen your stirrups, but for English I think they are ok.
The biggest thing I saw was to make sure you are not hunching and thumbs up like you said.
I don't think you were landing on Spiders back when you cantered, but like Equuestriaan said, you could lighten your seat a bit so you're not pumping as much.