Useful physics lectures can be downloaded from several reputable sources, including PBS's NOVA and MIT's OpenCourseWare. The PBS NOVA archive offers a variety of physics-related content, while MIT provides specific courses such as Electricity and Magnetism and introductory physics lectures. Additional resources can be found in blog entries that compile lists of physics videos. These platforms serve as excellent references for students and enthusiasts seeking quality educational material. Overall, there are multiple avenues available for accessing valuable physics lectures online.