I can’t view the videos because I don’t want to hand over my email address and get spam for the next decade 
In general, I’d say that working in person with a trainer is more beneficial than just following an on-line program. One of the big problems with self-study in horses is that you miss a lot of the details of your own body language, posture, and timing that a trainer standing next to you would correct.
IME, body language, posture, position, form, for in-hand or ground work is a lot less complicated than in the saddle, but it is *equally important." If you are standing in a way that invites behavior you don’t want, your training won’t work. That includes inadvertently blocking your horse from going forward, or the opposite, inviting him to follow you when you don’t want it (“invade your space”). Or not being quick and precise enough, or not standing up tall enough, or not asking enough, or asking too much.
I did a good “training for courage” clinic a few years back with regional trainer, and have seen some other groundwork clinics and trainers as well. Basically, no matter how much they claim to have a system, they are basically working with the same set of concepts and techniques. In particular, keep your horse’s exposure to new, potentially scary, objects at the level of curious and interested. Stand between him and the object. Don’t act like you are training a puppy and use your high=pitched excited “what’s this? what’s this? OOO!” voice. Rather act like you don’t care about the thing, don’t even notice it. Go at the horse’s level of comfort. Walk by the tarp ten feet away multiple times before you start getting closer. If he starts to goggle, stay at that distance until he relaxes.
Don’t let the horse actually get afraid. Show him that you will recognize his comfort level and work within it.
Etc.
I see that Tristan has a dressage background, which might make it easier for a dressage rider to communicate with him. Also it might help with the transition to under-saddle work. But I would expect that he’s using the same basic techniques as the better sort of western horsemanship person.
The big question with anyone teaching humans how to do ground work, is how do they transition back to the saddle? Some ground work trainers (as we know) seem to keep their students out of the saddle permanently. Others, I’ve seen IRL, don’t have the feel and tact in the saddle that they have (and teach) on the ground. So if you want a program that integrates groundwork and riding, the riding component also matters.