This is a newer HD render of the RealTraps video demonstrating diffusion.
Most people have no way to hear what diffusors do or how they sound in a room. So this video explains diffusion in plain terms with no math, then lets you hear an acoustic guitar recorded in close proximity to five different surface types - a "well" diffusor, a poly diffusor, absorption, a bare wall, and a typical bookcase.
If you have technical questions about this video that require a reply, please do not post them here as comments. YouTube is not a good venue for a technical exchange. Instead, please post your questions in the Acoustics section of my Audio Expert forum:
http://the-audio-expert.freeforums.net/