learner.org has a multitude of streaming video clips for all content areas. In science, there are several teacher resources for classroom use as well as resources for professional development. Resources are grouped by grade band and extend up to college/adult.
Applications for Science Teachers: Teachers could use this site to find video clips for showing students scientific concepts. It is also great for teachers to learn more about common misconceptions in science- there are several clips of learners (young and old) struggling to understand science. Showing students video of other learners and their misconceptions is a great opportunity to illustrate metacognition. Several workshops and distance learning courses are also offered.