The Canter Oval
Etrak published this video on improving the carrying strength at the canter. The great thing about this exercise is that it’s highly adjustable to suit the horse. So if your horse is not very strong yet, you can keep the ends of the oval wider, but if the horse is strong enough then you can make the ends of the oval into V shapes to get more of a quarter pirouette.
Forward and Straight
I like this clip of Lilo fore from the 2012 Region 8 Adult clinic series. It highlights the need for forward energy in whatever gait you choose, and to carry the energy into/through the downward transitions. Something I have a bad habit of not doing.
Canter Spiral In/Out
This one is a familiar exercise to most of us, but this video has some good comments on why it’s a good exercise and how to ride it. It’s a fairly short clip.