Well, do keep in mind a lot of these horses are WP horses as well so they are worked and trained to go so slow. If you want Sandy to canter similar this speed, its going to take a lot of seat and legs. I've gone to plenty of open shows with my qurab and now TB, where classes are exactly like this. Obviously my TB moves out much more than my Qurab, but that's beside the point.
It took a long time to get my Qurab to have a slow, easy going canter. Its just takes lots of consistent work.
here's an example of us, not the best but it gives you kind of an idea of the speed you should be aiming for if your serious about it.