I have interviewed Prof. Miro Zeman from Delft University of Technology. He has been teaching course called Solar Cells for several years. The course belongs to the OpenCourseWare, which means that the course material is available online for everybody including lecture materials and course book chapters. In addition, he has recorded all his lectures that are also available online. A link to his course is given here.
Prof. Zeman said the students are grateful for the lecture recordings but the recordings are not intended to replace the contact lecturing. He prefers to have direct contact and interaction with students during his lectures, which is not possible through recorded videos. He has found out that the students are mainly using the lectures i) if they miss the real lectures ii) when preparing for the exam. I asked if he knows how much the videos are being watched, also by outsiders, but he didn’t know that. My guess is that if people find the web page, quite many people watch the recordings as they are realized very well both substance and technical wise. I also asked if the videos have caused much extra work for the teacher, also in the form of more questions, but this was not the case.
Prof. Zeman also mentioned that TU Delft is offering a series of virtual and remote experiments for the students via internet here. Wow!