Which buddhist traditions use silent visual applause, instead of clapping, to show appreciation and what is the origin of this practice? In sanghas following the tradition of Zen Master Thich Nhat Hanh, to show appreciation one does not clap, instead one flaps his/her hands. This silent visual applause is similar to the sign for applauds in American, British, French and possibly other sign languages used by deaf persons.

Which other buddhist traditions also use silent visual applause to show appreciation? What is the origin of this way of showing appreciation in buddhism, was it borrowed from a sign language, and if so where and when?
This video says that it's widespread among French and German university students, ecologists, especially left-wing, for example at political assemblies and unions. And it says that an internet search shows that it's part of the "language of signs" but that no-one knows which country it began in.

The page Monks and nuns from the Thich Nhat Hanh collective, in Plum Village, France, pay our school a special visit suggest that Thich Nhat Hahn are:


From France
Teaching 'silent applause'
Teaching 'ecologist' songs such as "I love nature"


So perhaps they adopted the gesture from that milieu (or vice versa): i.e. from European students and young ecologists.