Not! You can do this if the horse is walking or trotting — but you should not have to “emergency dismount” in that case.
But I would not recommend this when the horse is running. The dynamics just won’t work.
If we do some basic physics, we find that hitting the ground at 10 mph-30 mph (in a vertical, i.e., “up and down,” speed) would be like falling from 3.36 to 30.15 feet. The first, yeah, I can do it. That latter — no way!! No thank you!!
Thinking of energy considerations, your final “energy of motion” is equal to your initial “energy of height:” the higher the height you jump from, the faster you go upon landing, and the more it hurts — when it gets to the point that it starts hurting.
If we measure “energy of motion” and “energy of height,” we get that 1/2mv^2 = mgh, where m is your mass, g is acceleration due to gravity, h is your height of fall, and v is your final velocity.
When you come off a horse, you are not always going straight down; part of your motion is straight down, but part is along the ground. We could break the motion into two parts like that. Reality is OK with it, that’s why we do it in physics. We’ll be using only the up and down, the vertical, part in our calculations.
Now if we solve for h, we get h = v^2/(2g).
We’ll use feet and seconds in our calculations, to end up with a height in feet. In feet/seconds^2, gravitational acceleration is 32 ft/s^2.
Then for hitting the ground at a 10 mph = 14.67 ft/s vertical speed, it is as if you jumped from a height of h = (14.67)^2/(2*32) = 3.36 feet.
For hitting the ground at a 15 mph = 22 ft/s vertical speed, it is as if you jumped from a height of h = (22)^2/(2*32) = 7.56 feet.
For hitting the ground at a 20 mph = 29.33 ft/s vertical speed, it is as if you jumped from a height of h = (29.33)^2/(2*32) = 13.44 feet.
Ok, here, I’m not landing on my feet. No, thank you.
For hitting the ground at a 25 mph = 36.67 ft/s vertical speed, it is as if you jumped from a height of h = (36.67)^2/(2*32) = 21 feet.
But for hitting the ground at a 30 mph = 44 ft/s vertical speed, it is as if you jumped from a height of h = 44^2/(2*32) = 30.25 feet.
No thank you!!! Really no thank you.
But if you can land on a dime and stay upright and in place when the horse is moving at 20-35 mph, good for you. Or if you could land like this, when the horse is running 20-35 mph, and take off in a run alongside your horse, good for you.
For the rest of us, we’d better learn to roll. My recommendation is that all horse riders study some Parkour. Save your knees and hips and back for other things in life than absorbing a hard fall.
Back to the video. They say you “might” need to do an emergency dismount some time? hahahaha That’s funny. I guess that’s true if you do nothing other than walk in a round ring on a sedate horse that is pretty much unresponsive to its environment.
But if you do anything beyond that, you’re going to have to bail and take some falls. It’s not “may,” it’s “will.”
Many is the time I came off. Many is the time I got right back on.
My recommendation: learn to come off your horse if you value your health. Learn to ride, yes, so you minimize the times you come off, but learn to come off, because it will happen.