Crash Course: Youtube; short courses about a variety of topics
Crash Course Kids: Youtube; delves into grade school science topics
Discovery Virtual Field Trips: science-focused virtual fields trips
NASA: ultra high-definition videos from NASA about space and space exploration
Periodic Videos: Youtube; videos on the elements of the periodic table and other chemistry news
Sixty Symbols: videos on scientific symbols, what they mean, and the history behind it
Smithsonian: Youtube; videos on the natural world
SciShowKids: Youtube; fun, complex science concepts for young, curious minds.