This video says about itself:
Staurois latopalmatus: male foot-flagging behavior recorded in Danum Valley, Sabah, Borneo during a study on visual and acoustic signals in Anura.
Video by D. Preininger & M. Boeckle (recorded in Feb. 2006)
From Wildlife Extra:
Rainforest frog shakes a leg
March 2010. An extremely rare video clip of a Bornean ‘rock skipper’ frog communicating by waving its legs has been captured by researchers from The University of Salford has released.
Waving legs used for communication
The frogs wave their legs because they live in fast-running streams where the background noise is so loud that it is difficult for them to communicate with each other by calling. The waving notifies other males of their presence and it also used to attract females.
The behaviour was observed on a postgraduate tropical ecology field course at the Danum Valley Field Centre in Sabah, North Borneo.
Rock skipper frog
The clip, filmed by University of Vienna students Doris Preininger and Markus Boeckle, captures a rock skipper frog waving its legs at the edge of a stream – a behaviour that was discovered around twenty years ago but has only recently been thoroughly investigated.
Robert Jehle, from the University’s of Salford said: “This video clip shows an exceptionally rare phenomenon, and at the same time serves as a good example of what we lose through the cutting down of rainforests.”