I found the following video, which I would like to recommend as an introduction into Ethics. It is from Harvard University, the lecturer is Michael Sandel. The lecture covers Utilitarianism and the Categorical Imperative and is very understandable. The lecture is very interactive and engaging (both for the audience and for the person viewing the video). The video addresses the classical ethical dilemma of a trolley which is about to crash into a group of 5 people. Would you steer the trolley to a side track on which there is only one person standing?

The complete series contains 12 videos, each one about 1 hour long. Here is a link to the series on youtube.