I've actually heard the "trumpet" sound, though it sounded more like some gigantic machinery grinding metal than a trumpet. It also seemed to come from the sky. I heard it twice, and it was entirely different than the sound in the clip. The other weird thing I noticed since I was walking my dog at the time, was that he had absolutely no reaction to it. That dog could hear cheese being unwrapped from a block away, and yet, no reaction to that particular sound.