I see what you are saying or highlighting in the video. The actual drill you see being performed was once known as the Mehlhorn Drill, where you move back and forth with a club against the legs. Think Mehlhorn had the club in front or that might have been Toski.
Found one site in English regarding Triangulaid and one with FlowMotion Golf. From what I can gleam that they have a method/system including some specific aids/drills. At the fundamental level, it appears to be about a free swinging motion which is what the Easiest Swing in Golf is about. That is about all I can see that really parallels them.
As far as the La Danse du Golf, it is more than just he Mehlhorn/Owens drill. It encompasses all 6 principles, the 3 don'ts and the #1 swing killer. Charles Marchildon videos do highlight the features, in fact I was leaning that Sparks might have worked with him in the 80s/90s when he worked in France, just basing it on some of features he highlights. Sparks claims it is his original work both in his book and I think in a video interview.,
Anyway back to both methods, this idea one's natural swing, tension free, free motion I believe is gold for the average golfer and especially for seniors. I am partial to The Easiest Swing in Golf cause of Julian Mellor's videos and some others. The explanation makes sense to me and after 10 months of working with it, I have reversed my degrading golf game and have less hip and back pain. I will add Owens to the list to follow and see what else pops up, but for now if it is working, stick with it, not that it can't get better with some adjustments.,
"The originality of TRIANGULAID lies in the coaching method, which is based principally on sensation, balance and coordination. Due to this, it is perfectly complementary with all other methods and allows players to discover their OWN Natural Swing. "