The Sun:
https://www.cea.fr/english/Documents/thematic-publications/sun.pdf
Proto-star
http://aspire.cosmic-ray.org/Labs/OldStarLife/starlife_proto.html
Enchanted Learning: Planets
Khan Academy: The Solar System and The Earth
For the full playlist of Astronomy videos you can check out the Crash Course playlist
NASA Space Place: All About the Planets