The best for me when a tree limb or fence rail or street sign post availbale for support situations is a Manfrotto 035 super clamp with a 1/4 or 3/8 stud in it.
It is as stable as what it is clamped to. I also have a head and about 4" of shaft from an old cheap tripod that allows for more flexible shooting with 35mm when it is bolted into the superclamp. With 6x6 I don't care if the camera ends up on its side with just the super clamp and stud to support it.
I also have a small tripod with about a 6" post, and three 8" legs, that I use to brace cameras against my chest. With slowed down careful breathing, and not too strong a wind I am good to 1/4 second with this thing.
The spring apart legs thing in the video looks neat, and is just the way my tent poles go togther. But rarely for me are the most interesting view points only where the ground is level, and the camers is 4" off the ground.