Certified Clinical Nutritionist Radhia Gleis gives a very clear explanation of what Gluten is and what Gluten Intolerance, Allergies, Sensitivities and Autoimmune Diseases are. There are some pretty 'graphic' pictures that help to imprint the explanations of effects of gluten intolerance. (I like how she is able to sock so much information into a very brief video and there are no supplements being promoted).
She does tend to push the Hunter/Gatherer belief system that I don't necessarily subscribe to (eg., People with O blood type are "hunter, gatherer ancestors and they have a genetic predisposition to the gluten intolerance; A blood types are better able to deal with grains. Hmm) It's interesting, nontheless.