Check out the tölt, the smooth gait where the rider seems to float through the air on the horse. Compare this to the bouncy trot which some riders are using for training or to to cross some rough terrain.
Yes, it is common for a herd to go loose like this. They follow the lead riders although you will see some free-lancers who have no problem getting back in line. All over the country you can see horse trails like this one along the side of the roads.
Notice how the riders take a break and get off the horses so they can rest. This is also typical. They will ride at a good clip, in tölt, of course, for about a half hour and then let the horses rest and graze. With a loose herd, very little is done at a walk!
Everyone, especially the horses, enjoys an outing like this!
So, where is this valley, anyway?