There are many resources on Internet to learn biology and understand used technics. iBiology is one of them, and a great one ! You can find informations on many domains from cell biology to synthetic biology and many talks on peripherical topics (impact on society, ethics, laws, etc.)
Close to our own skills, we advise you to look at courses on light microscopy (Basic Microscopy and In-depth Microscopy)

Biology’s mission is to convey, in the form of open-access free videos, the excitement of modern biology and the process by which scientific discoveries are made. Our aim is to let you meet the leading scientists in biology, so that you can find out how they think about scientific questions and conduct their research, and can get a sense of their personalities, opinions, and perspectives. We also seek to support educators who want to incorporate materials that illustrate the process and practice of science

Source: iBiology