This YouTube clip is from some documentary -- perhaps the more knowledgeable of you can identify it.

In this clip of a minute or so, Martin Hayes speaks of being very young when Tommie Potts brought his fiddle and did a show-and-tell of how never to play a tune the same way twice. The video within the clip combines Martin Hayes, in color, in an on-camera interview, with Tommie Potts, black and white, playing the fiddle on camera.

Martin Hayes on Tommie Potts