There's some (silent) film of Butterworth dancing here: https://www.youtube.com/watch?v=X7UZ4WXI9sc

and here (With an inappropriate musical backing!), together with Cecil and Maude: https://www.youtube.com/watch?v=tI5qxjWutrs

There are some more details about the singers he collected the songs from here: https://en.wikipedia.org/wiki/The_Banks_of_Green_Willow