A videocast of Dr. Alfred Sommer's lecture during the Global Health Vision Lecture series from December 2014 can be viewed here:
Dr. Alfred Sommer presents a four-part lecture on the major causes of preventable blindness: mature cataract, onchocerciasis, xerophthalmia, and trachoma.
Dr. David Friedman presents a two-part primer on how to travel safely and serve effectively as a volunteer physician abroad.