I have never seen this before but I was wondering if I'm just not familiar with the practice. I was watching a video of a horse and rider combination at a show, the rider who was actually riding was a younger-looking pro. The person said to be riding was a junior. Is this usual or cheating? It wasn't a warm-up round.
It's a mistake. Sometimes, you can look through results and find them. They can be quite entertaining; I remember one time, it said that Patricia Griffith was both riding and training a small pony in the small pony hunters. I couldn't help but laugh at the image of her in jods and garters - she's so tall!
This is a little vague. Was the juniors name in the video via scoreboard or announcement, or in the video description? Obvously it would be very easy for the latter to be a mx up.
Also, "not a warm-up class" doesn't mean it wasn't the pro schooling a horse for a junior anyway. For instance, a 1.25+ class might not be a warm up to some, but it often is for others. There are no clear round ribbons at those heights, so if they néed the school, they pay their full fees and go.
There was a funny thread on here years ago about a Grand Prix rider listed in the results of an adult equitation class. Needless to say, it was a clerical error, but some people got very whipped up at the idea!
I've had my name announced as my trainer and vice-versa, just a mistake most likely. I've also had my name announced for a junior class and as myself in an adult ammie class on the same day when I let someone borrow my horse for a couple of junior medal classes. In all cases the recorded results that went to USEF were correct. Chalk it up to human error.