A couple of months ago, I mentioned that I had seen Grand Wizard Theodore, the inventor of the turntable scratch, perform during a class I was attending at Scratch Academy. During his performance, Theodore talked about how he initially came up with the scratch and then put on an amazing demonstration of turntablism. The above video is taken from an earlier class rather than the one I was at, but nevertheless the routine is almost identical. At around :56 of the video, Theodore begins telling the story of inventing the scratch. Unfortunately the video cuts out right before he begins his demo of blind needle dropping, easily the best part of his demo, but at around 3:30 things get pretty interesting as he cuts up a guitar sample with his elbow.
And if you've never seen it before, here's a clip of Theodore using needle drops instead of record scratchs (which is what dj's had to do before the crossfader was invented) to cut up a song: