This is video of a talk given last year by David Dixon, assistant professor of math, science and engineering at Saddleback College in California. He used to work in the Physics Department at California Polytechnic State University, which, like many physics departments around the world, received loads of correspondence from non-scientists who thought they had come up with earth-shattering, game-changing hypotheses that needed to be shared.
Now, sometimes, laypeople come up with good ideas that should be explored. But many of these letters are better classified as the work of cranks — folks who had big ideas, cared deeply about those big ideas, but who were dead wrong ... and utterly impervious to the idea that they might be wrong.
In this talk, Dixon delves into the collection of crank letters received by California Polytechnic State University over the years to explain the hallmarks of crankitude, the behaviors that raise red flags for professional scientists, and what we can actually learn about real science by studying fake science.
YouTube says the video is over two hours long, but that's apparently inaccurate. The actual talk is an hour long and just somehow got loaded twice into the same video.
If this is a topic that interests you, I'd also recommend reading this MetaFilter thread, where scientists explain to a poster why the poster's friend is setting off crank red flags with scientists whose attention he's trying to capture. It's a fascinating look at what to do and what not to do if you have a hypothesis you want to share.