iBioSeminars is a site that contains free Biology videos. The videos are on-demand lectures that are available to view online or download. Each video starts with an extended introduction so that students can understand the topic better. They are mainly geared towards college, but teachers could use them to review concepts or learn about new topics and they could also be used with AP Biology classes.
There is an education page on the site that has lecture notes, questions and answers, and short video clips to use for teaching. The videos cover a huge range of Biology topics and subjects.