Here' a really good RGM. The builder tips his hand a little though. They start the video with the machine working perfectly, and it takes a little over a minute. It is really impressive, well built, and it doesn't look too cheesy, like some RGM tend to look, but after it runs perfectly, the author spends the rest of the six minutes showing failure after failure after failure. It shows you just how hard it is to make one work.
What I find stunning is the silence. If one of my creations failed that many time, I assure you, I would not be silent. "Beeeeeeeeeeeeeeeeeep"