Jumping onto a horse in movie stunts

Sometimes they really jump onto the horse. Here's one example...

In the movie Krull, a stuntman is shown attempting this move when they capture the Fire Mares. They cut the beginning of the jump so you think it's the actor, but you can tell the stunt man really jumps off the cliff and down and out about ten feet (or more?) to the horse. He lands on the horse and bounces off, falling to the ground. This is a trained stuntman attempting the stunt over a fairly short jump, and he fell (I expect they used the shot where he fell because to reshoot it would be dangerous and he may have been injured in the fall).

Here is the scene in question with the jump occurring around the 1:20 mark.

It's also important to note that the horse in this scene was almost certainly highly trained for this specific stunt. I think that, generally speaking, it would be unfathomably stupid to surprise an untrained horse (or any other large animal) in this fashion. Not only would it likely throw you, it might deliberately trample you. Given the danger involved--not only to the stuntman, but to the animal--I wouldn't be surprised if they usually just used editing and camera tricks.

I don't think it is practical in real life due to safety reasons you mentioned. But as far as the stunt shooting goes they can perform it using below tricks:

1) They can use rope so the landing would be easy. This is a general trick used when the height jumping stunt is performed. The camera team them increase/ decrease the speed as per their requirement and make it look like real.

2) If person is relatively at small height then they can shoot the jumping sequence and then they change the ending by showing the person directly on the back of the horse. As the chase sequence generally starts by end of this scene, very few people can catch if they have made any mistake in it.