This is 2-part video on psychopathy by an undergraduate Canadian student, who is majoring in psychology and also works in a lab investigating psychopathy. She gives a description of this personality disorder known as psychopathy, including history and statistics. She may go a little fast for some, but she is personable and clear. She is modest about her presentation, but she does an excellent job of presenting this clinical information.
(Her point about twins studies, though, is very brief and perhaps unclear on this video, so, if you’re interested, you may want to do more research on that.)