Hi Alan,
thanks for the circular breathing videos; they seem to be very instructive (although I don’t understand why the flute player wants the tongue to be moved back…).
One thought about circular breathing with the Vibrandoneon: I think it was Melodica-Me who had problems with this, and I had, too. I ran out of air much too fast. But then I simply tried to cover half of the pipe hole with my upper lip to lose less air, and it works much better now.