Dave is one of the co-founders of Udacity and I believe to be a very engaging lecturer. Udacity and coursera have a very different approach to education. Coursera is more like a traditional university with start and end dates for courses and a weekly schedule of content. Udacity is open 24/7 with short 5 minute snippets with quizzes in between and homework assignments at the end of each section.
I'd watch Peter Norvig's ted lecture, which was the inspiration for Udacity to get a better idea:
http://www.ted.com/talks/peter_norvig_the_100_000_student_classroom.html
For Boneh's course, it is nearly identical to his for credit class for Stanford's SCPD master's program: http://scpd.stanford.edu/search/publicCourseSearchDetails.do?method=load&courseId=11792. Probably in the next five or six, years it will be offered for full college credit.