Video Solutions: Just like an instructor working a problem at the board, only better! Fast forward or watch parts again and again.
PhET Simulations: Use these simulations to check your answers on worksheets and homework or just to visualize the concepts. Great for circuits.
Khan Academy: Video lectures covering all of Phy 4A, 4B, and 4C. Great if you are not understanding something or missed a lecture.
HippoCampus.Org: Well done, multi-media videos that highlight certain concepts and topics.