Acids, Bases, and the pH Concept - AP Chem Unit 8, Topic 1a 

In this video, Mr. Krug discusses the difference between strong and weak acids, as well as the difference between strong and weak bases. He introduces students to the autoionization of water and the relationship between hydronium ion concentration and hydroxide ion concentration. He finishes the video by showing how to calculate pH, and how to calculate hydronium ion concentration given the pH.