Anyone Know this Hanging Technique

Where you stand and hang straight down then use your hand to lift at the underside base of the penis and either hold in that lifted position or curl it, up, and down down.

Saw a clip of that PE expert guy from California (Phallocare?) doing it.

If it’s a good thing to do is it to better stretch ligs or some other aspect of the penis?

It’s like fulcrum hanging - if I understand you well. Fulcrum hanging in my experience - according to where you place the fulcrum (which may be your hand or a rounded soft object, or a rice sock, puts enormous stretch to the tunica (rather localized). It also has some resemblance to certain manual exercises, check this new thread Why “progressive bends” SHOULD deliver huge gains