Princess is loping in the same lead going both directions (on purpose) so you can see the "3 beat trail canter" from both sides! If you watch the right front and left rear you will see that they are moving diagonally, causing two beats. Next focus on the left front and right rear and take notice how they are moving at the same time in the same direction, causing only one more beat as they hit the ground at the same time. Thus, the 3 beat pattern.

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