I take it from the other responses to this that by "pre-lectures" you mean audio- or video-recorded lectures that students watch or listen to before class?
I've had great success going slightly lower tech by just having the students read the textbook before class. I have my students complete pre-class reading quizzes (graded on effort) as motivation for completing the reading. I usually have 80-90% of students come to class with something they've learned from the reading.
My guest post on ProfHacker from back in March has lots more details about this system:
Derek Bruff, Ph.D.
Assistant Director, Center for Teaching
Senior Lecturer, Department of Mathematics
From: David Wilson [mailto:[log in to unmask]]
Sent: Tuesday, September 07, 2010 10:48 PM
I am implementing pre-lectures into my second semester general chemistry class this semester. Early observations are fairly positive. It is nice hearing students use fancy terms like "microstates" during class discussions. Has anyone else had experience implementing pre-lectures? I would love to hear about any successes and challenges.
Associate Professor of Biology and Chemistry
Champaign, IL 61821