Massachusetts Institute of Technology led the way in providing free access to the content of course material via their MIT Open CourseWare initiative. Although credit is not awarded for the courses, they are a great way to refresh your knowledge or to learn subject matter anew. Lots of professors have gained popularity through these videos. To wit: Dr. Walter Lewin's lectures on Electricity & Magnetism, which are replete with demonstrations using animate (student) and inanimate objects as part of the show. He covers all the classical topics like charges and fields, solenoids and dipoles, Poynting vectors, oscillating charges, and radiation pressure. Digressions into talks on levitating bullet trains and the aurora borealis keep things interesting. Enjoy.